Classification of Children With Specific Language Impairment Longitudinal Considerations Research Article
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Research Article  |   October 01, 1999
Classification of Children With Specific Language Impairment
 
Author Affiliations & Notes
  • Gina Conti-Ramsden
    Centre for the Study of Language Impairments University of Manchester Manchester, United Kingdom
  • Nicola Botting
    Centre for the Study of Language Impairments University of Manchester Manchester, United Kingdom
Article Information
Language Disorders / Specific Language Impairment / Language / Research Articles
Research Article   |   October 01, 1999
Classification of Children With Specific Language Impairment
Journal of Speech, Language, and Hearing Research, October 1999, Vol. 42, 1195-1204. doi:10.1044/jslhr.4205.1195
History: Received October 24, 1997 , Accepted February 17, 1999
 
Journal of Speech, Language, and Hearing Research, October 1999, Vol. 42, 1195-1204. doi:10.1044/jslhr.4205.1195
History: Received October 24, 1997; Accepted February 17, 1999

This paper reports on the longitudinal results of a large project involving 242 seven-year-old children attending language units in England. Following our work outlining 6 subgroups of children with language impairment (Conti-Ramsden, Crutchley, & Botting, 1997), we examine the stability of the 6 subgroups of children with specific language impairment already identified, using data collected from the same children at age 8 years. The findings suggest there is considerable stability in the patterns of difficulties delineated by the classification system involving 6 subgroups. Poorer stability was evident in the classification of the children across time with 45% of children moving across subgroups. The membership stability of the proposed classification system was very similar to that found when the children were classified into 3 subgroups following another well-known system (Rapin, 1996). The findings are discussed with particular reference to issues surrounding the classification of children with SLI.

There has been much discussion both in the literature and in current practice regarding the heterogeneous nature of children with specific language impairment and the usefulness of the term specific language impairment (SLI; Leonard, 1987; Leonard, 1991; Miller, 1996). On the one hand, the debate has centered on the specific or otherwise nature of the language problem these children have (Aram, 1991; Johnston, 1991; Tomblin, 1991). On the other hand, authors have attempted to find subgroups of children with language impairment in an attempt to address the heterogeneity issue. Rapin and Allen (1987) for example, outlined six subgroups of children referred for speech and language problems on a clinical basis. Bishop (1994), Bishop and Edmundson (1987), and Wilson and Risucci (1986) have also produced reports on the differing groups of children who may all be described as having SLI. In a previous paper, we also outlined six subgroups of children who were attending language units using a hybrid technique involving (a) statistical “clustering” technique on standard assessment scores and (b) teacher opinion (Conti-Ramsden, Crutchley, & Botting, 1997). Five of these groups were closely related to those of Rapin and Allen (1987): Cluster 1 (lexical-syntactic deficit syndrome), Cluster 3 (verbal dyspraxia), Cluster 4 (phonologic programming deficit syndrome), Cluster 5 (phonological-syntactic deficit syndrome), and Cluster 6 (semantic-pragmatic deficit syndrome). It needs to be noted that the terminology used for the cluster names in this paper is that of Rapin and Allen (1987).
Most of the research that has examined the different profiles of children with SLI has done so on a cross-sectional basis. That is, subgroups have been identified from a group of children varying in age and for whom data are available at a single point in time. An exception to this is the study by Bishop and Edmundson (1987) which examined the prediction of outcome based on standardized tests at 4 years of age. Although there is some merit in classifying children at one point in time (in that it may provide a description of potential difficulties and may be generalizable to other samples and ages), it is of interest to clinicians and researchers to know how reliable the classification system is over time. Given that standardized tests are not perfectly reliable, some variation may just reflect random “noise,” that is, a particular child may have a different profile from Time A to Time B not because of any real change in the child but because of fluctuations in test scores from extraneous reasons. Therefore, the issue of the stability of subgroup membership over time is an important element in the categorization process.
Consequently, the present study attempts to add to our knowledge of subgroups of children with SLI by studying a large cohort of 8-year-old children with SLI for whom data were also available at 7 years of age (Conti-Ramsden, Crutchley, & Botting, 1997). The investigation addressed the following questions:
1. What is the stability of the six subgroups of children in the original sample aged 7 years in terms of the types of profiles of difficulties delineated by the classification system (stability of test score patterns)?
2. To what extent do children with SLI remain in their original cluster grouping after 1 year, and to what extent do they move across clusters (stability of children’s classification)?
3. Is the membership stability of our six subgroups of children similar to that of another well-known classification system (Rapin, 1996)?
Methods
Participants
A group of 242 children with specific language impairment (SLI) took part in the study. They were recruited from 118 language units attached to English mainstream schools. Language units are language-based classrooms for children with SLI. In order to be placed in a language unit, children generally have to fulfill a number of criteria. Most units in England require children to have statements of special educational needs (or to be undergoing assessment for one) that details their difficulties and the professional input they require including intensive speech and language treatment. Specific criteria for entry varies from Educational Authority to Educational Authority across England. Unit criteria generally require that the child fall within the normal range on nonverbal cognitive measures; that, although minor associated physical, emotional, or behavioral difficulties may be present, the language disorder must be the child’s primary problem (usually established by discrepancy between the child’s language assessment and cognitive assessment); that the child would find it difficult to cope in mainstream education even with support and needs a full-time placement in a structured small group setting; and that children for whom English is a second language should demonstrate the same language difficulties in any other language(s) they speak. Unit provision is designed to prepare children with language impairments to return to mainstream schools. Thus, most children spend at least part of their school week in mainstream classes.
It was established (via telephone inquiries to all primary school-age language units) that throughout England approximately 500 Year 2 children (6;6 to 8;0 years) were spending 50% or more of the school week in such language units. The 242 participants who formed the study cohort represented a randomized sample of these children. Over 100 language units were visited and roughly half the eligible children in each unit were sampled. The cohort consisted of 186 boys and 56 girls (girls forming 23.1% of the cohort). Twenty-six children in the study were additionally exposed to a language (or languages) other than English at home (for further details see Crutchley, Botting, & Conti-Ramsden, 1997). These 242 children were studied and, based on teacher opinion and results of standardized assessments, were classified into six clusters or subgroups of language impairment (Conti-Ramsden, Crutchley, & Botting, 1997). For the purposes of this investigation, the children were seen again 1 year later for Time 2 of the project. At Time 2, 234 of the 242 children originally assessed continued to participate (age range 7;5 to 8;9 years). The socio-economic background of the children participating in the study resembled the distribution found in the general population. The indicator used was income per household which averaged approximately £18,000 per year in 1996/1997 in England (Office of National Statistics, 1998). In our sample, 53.1% of the participants came from households earning below £18,000 per year and 46.9% of the participants came from households earning more than £18,000 per year. Furthermore, there were no statistically significant differences across clusters in family income at either stage of the study (Time 1 and Time 2).
Measures
The test battery used for this study was intended to reflect a range of language-based and educational skills, using a selection of well known standardized assessments. All standardized tests were administered at Time 1 (age 6;6 to 7;9 years) and at Time 2 (age 7;5 to 8;9 years).
Standardized Tests
In total, seven language assessments were administered to the children as part of this study, and these are described fully in the report of the Time 1 results (Conti-Ramsden, Crutchley, & Botting, 1997). Briefly, the assessments were as follows: the Goldman Fristoe Test of Articulation: Single Word Level (Goldman & Fristoe, 1986), the British Ability Scales: Number Skills (Elliot, 1983), the British Ability Scales: Naming Vocabulary (Elliot, 1983), the British Ability Scales: Word Reading (Elliot, 1983), the Illinois Test of Psycholinguistic Ability: Grammatic Closure (Kirk, McCarthy, & Kirk, 1968), the Test for Reception of Grammar (Bishop, 1982), and the Renfrew Bus Story (Renfrew, 1991).
In addition to these language and educational assessments, children completed the Raven’s Coloured Matrices (Raven, 1986), a measure of nonverbal cognitive ability. A total of 233 children were able to complete the nonverbal cognitive assessment; 206 children scored above the 15.9 percentile (above –1 standard deviation), 24 children performed between the 2.5 and 15.9 percentile (between –1 and –2 standard deviations below the mean), and only 3 children performed below the 2.5 percentile, suggesting these 3 children had more global delays.
Analyses and Results
Stability of Test Score Patterns
In order to examine the stability of clusters over time, all Time 2 data on the six tests used to originally cluster the children at Time 1 were entered into a new cluster analysis (with six clusters specified). This excluded the ITPA Grammatic Closure Test which was not used in the cluster analysis at Time 1 because there was a higher proportion of missing data than on the other tests. The cluster analysis was done using the K-means cluster function of SPSS for Windows (see Anderberg, 1973 for a discussion of cluster analysis). The aim was to examine the degree of match between the two independent cluster analyses. For Time 2, complete information on test data was available for 207 of the 234 children participating in the study (27 children had missing data on one or more tests making them unsuitable candidates for clustering). Time 1 and Time 2 clusters are both shown in Figure 1. There appears to be a good match between Time 1 and Time 2 clusters for Subgroups 1 (lexical-syntactic deficit syndrome), 3 (verbal dyspraxia), 4 (phonologic programming deficit syndrome), 5 (phonological-syntactic deficit syndrome), and 6 (semantic-pragmatic deficit syndrome) and not a good match for Cluster 2 (“normal” group). Tables 1 and 2 show the mean percentiles and 95% confidence intervals for Time 1 and Time 2 clusters. An examination of the means and 95% confidence intervals for Time 1 and Time 2 clusters revealed no statistically significant differences between 5/6 test means for Cluster 1 (lexical-syntactic deficit syndrome) and Cluster 6 (semantic-pragmatic deficit syndrome); 4/6 test means for Cluster 5 (phonological-syntactic deficit syndrome); and 3/6 test means for Cluster 3 (verbal dyspraxia) and Cluster 4 (phonologic programming deficit syndrome). For Cluster 2 (“normal” group), there were significant differences in the means for all 6 test means examined.
Figure 1.

Cluster Profiles for Time 1 and Time 2

Cluster Profiles for Time 1 and Time 2
Figure 1.

Cluster Profiles for Time 1 and Time 2

×
Cluster percentile means and 95% confidence intervals for Time 1.
Table 1.Cluster percentile means and 95% confidence intervals for Time 1.
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 52 15.6
11.8 to 19.5
9.9
7.3 to 12.6
32.4
25.8 to 39.0
14.8
11.3 to 18.3
78.9
74.2 to 83.6
15.2
11.7 to 18.7
2   n = 16 40.0
27.8 to 52.2
50.9
36.9 to 65.0
54.7
45.7 to 63.6
28.2
20.2 to 36.2
64.9
52.8 to 77.0
52.3
41.2 to 63.4
3   n = 29 15.1
10.3 to 19.9
12.7
7.4 to 18.1
62.7
57.5 to 67.8
11.3
6.3 to 16.3
14.1
8.9 to 19.2
14.6
8.2 to 20.9
4   n = 23 54.7
47.0 to 62.3
26.8
18.0 to 34.5
36.6
27.3 to 45.8
16.8
9.9 to 23.8
23.1
15.1 to 31.1
43.3
34.8 to 51.7
5   n = 84 9.4
7.2 to 11.5
8.6
6.2 to 10.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
6   n = 25 30.8
22.7 to 38.8
14.9
10.3 to 19.5
52.0
42.5 to 61.5
66.3
60.0 to 72.6
78.4
68.1 to 88.7
19.4
13.1 to 25.7
Table 1.Cluster percentile means and 95% confidence intervals for Time 1.
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 52 15.6
11.8 to 19.5
9.9
7.3 to 12.6
32.4
25.8 to 39.0
14.8
11.3 to 18.3
78.9
74.2 to 83.6
15.2
11.7 to 18.7
2   n = 16 40.0
27.8 to 52.2
50.9
36.9 to 65.0
54.7
45.7 to 63.6
28.2
20.2 to 36.2
64.9
52.8 to 77.0
52.3
41.2 to 63.4
3   n = 29 15.1
10.3 to 19.9
12.7
7.4 to 18.1
62.7
57.5 to 67.8
11.3
6.3 to 16.3
14.1
8.9 to 19.2
14.6
8.2 to 20.9
4   n = 23 54.7
47.0 to 62.3
26.8
18.0 to 34.5
36.6
27.3 to 45.8
16.8
9.9 to 23.8
23.1
15.1 to 31.1
43.3
34.8 to 51.7
5   n = 84 9.4
7.2 to 11.5
8.6
6.2 to 10.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
6   n = 25 30.8
22.7 to 38.8
14.9
10.3 to 19.5
52.0
42.5 to 61.5
66.3
60.0 to 72.6
78.4
68.1 to 88.7
19.4
13.1 to 25.7
Cluster percentile means and 95% confidence intervals for Time 2 new cluster analysis (n = 207 children).
Table 2.Cluster percentile means and 95% confidence intervals for Time 2 new cluster analysis (n = 207 children).
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 30 13.7
9.2 to 18.2
3.5
2.0 to 5.0
33.8
26.6 to 41.0
12.9
8.0 to 17.9
84.0
77.8 to 90.3
14.3
8.7 to 19.8
2   n = 25 58.0
48.9 to 67.1
19.3
12.5 to 26.1
75.8
69.3 to 82.5
39.4
29.1 to 35.3
87.5
79.5 to 95.6
39.4
30.5 to 48.3
3   n = 38 30.7
15.3 to 32.2
17.4
10.5 to 24.4
69.7
65.1 to 74.3
12.0
8.2 to 15.8
21.5
16.4 to 26.6
17.7
11.3 to 24.2
4   n = 19 44.2
33.4 to 54.8
21.8
13.8 to 29.7
26.0
18.4 to 33.6
12.9
8.2 to 17.5
54.8
41.0 to 68.7
55.1
45.7 to 64.6
5   n = 77 11.7
8.6 to 14.9
7.2
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
6   n = 18 26.8
16.5 to 37.0
14.7
8.6 to 20.9
53.2
39.8 to 66.5
68.7
60.2 to 77.3
60.3
46.0 to 74.6
18.8
10.8 to 26.
Table 2.Cluster percentile means and 95% confidence intervals for Time 2 new cluster analysis (n = 207 children).
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 30 13.7
9.2 to 18.2
3.5
2.0 to 5.0
33.8
26.6 to 41.0
12.9
8.0 to 17.9
84.0
77.8 to 90.3
14.3
8.7 to 19.8
2   n = 25 58.0
48.9 to 67.1
19.3
12.5 to 26.1
75.8
69.3 to 82.5
39.4
29.1 to 35.3
87.5
79.5 to 95.6
39.4
30.5 to 48.3
3   n = 38 30.7
15.3 to 32.2
17.4
10.5 to 24.4
69.7
65.1 to 74.3
12.0
8.2 to 15.8
21.5
16.4 to 26.6
17.7
11.3 to 24.2
4   n = 19 44.2
33.4 to 54.8
21.8
13.8 to 29.7
26.0
18.4 to 33.6
12.9
8.2 to 17.5
54.8
41.0 to 68.7
55.1
45.7 to 64.6
5   n = 77 11.7
8.6 to 14.9
7.2
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
6   n = 18 26.8
16.5 to 37.0
14.7
8.6 to 20.9
53.2
39.8 to 66.5
68.7
60.2 to 77.3
60.3
46.0 to 74.6
18.8
10.8 to 26.
Stability of Children’s Classification
The movement of children between clusters is shown in Table 3. Cluster data for Time 1 and Time 2 were available for 201 children. Fifty-five percent (111/201) of the children remained in the same clusters, and this proportion is reflected in each cluster considered separately, kappa = 0.43, confidence intervals = 0.34 to 0.51. Consequently, 45% of children moved clusters from Time 1 to Time 2, suggesting relative instability in the children’s cluster membership across time.
Movement of children across clusters from Time 1 to Time 2 (n = 201 children).
Table 3.Movement of children across clusters from Time 1 to Time 2 (n = 201 children).
Time 2 clusters
cluster 1 cluster 2 cluster 3 cluster 4 cluster 5 cluster 6
cluster 1 18 3 4 5 8 3
cluster 2 8 3 4 1
Time 1 cluster 3 1 15 10
clusters cluster 4 1 6 4 8 2 1
cluster 5 9 11 2 51 2
cluster 6 1 8 1 11
Table 3.Movement of children across clusters from Time 1 to Time 2 (n = 201 children).
Time 2 clusters
cluster 1 cluster 2 cluster 3 cluster 4 cluster 5 cluster 6
cluster 1 18 3 4 5 8 3
cluster 2 8 3 4 1
Time 1 cluster 3 1 15 10
clusters cluster 4 1 6 4 8 2 1
cluster 5 9 11 2 51 2
cluster 6 1 8 1 11
×
Movement of Children Across Clusters: Addressing Test-Retest Reliability
As emphasised previously, whereas cluster profiles remained stable across time (i.e., the means of tests for each cluster at Time 2 were not significantly different from Time 1) a substantial number of children moved cluster membership due to individual change in test scores. It is important to address the question of whether this fluidity of cluster membership might be the result of poor test-retest reliability in the measures used. We therefore examined the major shifts of group (those moves made by 8 or more children) to determine the degree of test score change. Moves in cluster membership are not usually caused by a change in performance on all measures, but rather by a significant clinical shift in one or two areas of language skill and secondarily by lesser changes in other assessment scores. Thus we identified the tests in each movement group that appeared to represent the most change. Table 4 below lists the mean, minimum, and maximum changes in score on the test(s) identified as the major cause of movement for each cluster. These can be compared with the overall cohort changes presented in Table 5.
Change of test score in movement groups.
Table 4.Change of test score in movement groups.
Movement group (n) Test of interest Minimum change Maximum change Mean change (SD)
1 to 5 (8) GF-Articulation* –22 percentiles –66 percentiles –41 (13) percentiles
3 to 5 (10) BAS Naming V* –6 percentiles –37 percentiles –24 (12) percentiles
5 to 1 (9) GF-Articulation* +23 percentiles +91 percentiles +55 (28) percentiles
BAS Naming V –2 percentiles +57 percentiles +20 (19) percentiles
5 to 3 (11) BAS Naming V* +14 percentiles +67 percentiles +45 (18) percentiles
6 to 2 (8) GF-Articulation* +0 percentiles +59 percentiles +9 (21) percentiles
BAS Naming V –3 percentiles +46 percentiles +18 (19) percentiles
Bus Story –20 percentiles +62 percentiles +27 (26) percentiles
TROG –13 percentiles +65 percentiles +20 (24) percentiles
Table 4.Change of test score in movement groups.
Movement group (n) Test of interest Minimum change Maximum change Mean change (SD)
1 to 5 (8) GF-Articulation* –22 percentiles –66 percentiles –41 (13) percentiles
3 to 5 (10) BAS Naming V* –6 percentiles –37 percentiles –24 (12) percentiles
5 to 1 (9) GF-Articulation* +23 percentiles +91 percentiles +55 (28) percentiles
BAS Naming V –2 percentiles +57 percentiles +20 (19) percentiles
5 to 3 (11) BAS Naming V* +14 percentiles +67 percentiles +45 (18) percentiles
6 to 2 (8) GF-Articulation* +0 percentiles +59 percentiles +9 (21) percentiles
BAS Naming V –3 percentiles +46 percentiles +18 (19) percentiles
Bus Story –20 percentiles +62 percentiles +27 (26) percentiles
TROG –13 percentiles +65 percentiles +20 (24) percentiles
Whole cohort changes on tests.
Table 5.Whole cohort changes on tests.
Test Minimum change Maximum change Mean change (SD)
GF-Articulation –66 percentiles +92 percentiles +3 (26) percentiles
BAS Naming Vocabulary –60 percentiles +81 percentiles +9 (24) percentiles
BAS Word Reading –41 percentiles +95 percentiles –0.5 (12) percentiles
BAS Number Skills –48 percentiles +70 percentiles –2 (12) percentiles
Bus Story –58 percentiles +63 percentiles +3 (17) percentiles
TROG –40 percentiles +65 percentiles +5 (18) percentiles
Table 5.Whole cohort changes on tests.
Test Minimum change Maximum change Mean change (SD)
GF-Articulation –66 percentiles +92 percentiles +3 (26) percentiles
BAS Naming Vocabulary –60 percentiles +81 percentiles +9 (24) percentiles
BAS Word Reading –41 percentiles +95 percentiles –0.5 (12) percentiles
BAS Number Skills –48 percentiles +70 percentiles –2 (12) percentiles
Bus Story –58 percentiles +63 percentiles +3 (17) percentiles
TROG –40 percentiles +65 percentiles +5 (18) percentiles
×
As can be seen, the moves are substantial and represent real clinical changes in profile, especially compared to whole-cohort changes. In most groups, even the most conservative changes in score are quite large and are all in one direction. This is not so clear for the children moving from Cluster 6 (semantic-pragmatic deficit syndrome) to Cluster 2 (“normal” group). These data support the argument made previously that Cluster 2 children are difficult to include in a classification of language impairment because their profiles appear normal on average on the measures used in this study.
It is also important to note that the changes that result in cluster membership shifts are not in the same direction for each movement group. For example those moving from Cluster 1 (lexical-syntactic deficit syndrome) to Cluster 5 (phonological-syntactic deficit syndrome) all show a marked decrease in articulation skill for age, whereas those moving from Cluster 6 (semantic-pragmatic deficit syndrome) to Cluster 2 (“normal” group) all show an increase in articulation score. If score changes simply were due to test-retest reliability difficulties, we would expect firstly to see a random pattern of change (in both directions for each subgroup). Or if the test showed a systematic positive bias for scores to, say, improve on second testing, then one might expect that systematic rise in scores to be reflected across all subgroups in the same increasing direction. As already mentioned, neither of these patterns were the case in data obtained from this study. Instead, strong directional shifts were seen in different subgroups, some all increasing, others all decreasing. Secondly, the magnitude of the changes observed should be relatively small, assuming that these tests are reliable to some extent, which clinical experience and, in some cases, reported reliability coefficients (see below) suggest they are. In contrast, the changes observed in this study were large. Thirdly, each movement group showed at least one test where all children moved uniformly in a given direction (marked “*” on the table), a pattern not predicted by measurement error.
Unfortunately, not all the tests used report adequate test-retest information (means and SD at both time points) making it difficult to determine their reliability boundaries. In addition, numbers of children moving clusters were too small to allow statistical analysis (which may have confirmed that the moves across subgroups were unlikely to be caused by random measurement error). However, it is highly unlikely that any standardized test would have such poor reliability that all scores at Time 2 would show these patterns of change from Time 1 by chance or through measurement error. Reported test-retest reliability was available for the BAS number skills test at 0.95. In addition, the Goldman-Fristoe test and the BAS word reading test, which appear to be two major factors in cluster movement at this age, report a 0.95 median agreement for ± errors in production of words and a 0.97 test-retest reliability coefficient respectively. It has been pointed out (Wilcox & Morris, 1995) that at certain ages relatively small changes in performance on tests such as the Goldman-Fristoe may lead to large changes in percentile score (i.e., improvement on 4 or 5 items may result in 30 to 40 percentile changes). However, this is the nature of standardized tests. The percentile score represents age-related information for the very reason that raw scores can be misleading. It may be that, at a certain age, a four-item change represents a significant clinical improvement, whereas, at another age, the same increase in raw performance leads to little change in normalized scores. Consequently, it is possible that relatively small changes in articulation may have shifted children from Cluster 1 (lexical-syntactic deficit syndrome) to Cluster 5 (phonological-syntactic deficit syndrome) and from Cluster 6 (semantic-pragmatic deficit syndrome) to Cluster 2 (“normal” group). Nonetheless, it needs to be pointed out that cluster analysis compares scores on all the tests used for clustering, of which articulation is one, albeit important, factor.
Thus, taking all the above evidence into consideration, it appears that the majority of movements of children across clusters were due to genuine clinical change in language profile.
Membership Stability: Comparison With Rapin’s (1996) System
The starting point for the comparison with Rapin (1996) was theoretical in nature. It had been found that 5 of our 6 clusters matched very closely the subgroups proposed by Rapin and Allen (1987). In 1987, Rapin and Allen proposed six subgroups of SLI: lexical-syntactic deficit syndrome, verbal auditory agnosia, verbal dyspraxia, phonological programming deficit syndrome, phonological-syntactic deficit syndrome, and semantic-pragmatic deficit syndrome. One of our clusters, Cluster 2 (“normal” group), had no match with Rapin and Allen’s categories and was composed of children who appeared to be performing within the normal range (the children’s test scores for language measures were above the 40th percentile and for word reading above the 28th percentile). There were 16 children in Cluster 2 (“normal” group), and these children were not included in the next step of the analysis. In addition, Rapin and Allen (1987) had a further subgroup in their categorization system, that is, children with verbal auditory agnosia.
No such children were found in our cohort. Furthermore, it is also the case that auditory agnosia is no longer considered SLI (e.g., it is usual for auditory agnosia to be prevalent with seizure disorders). Thus, it is not surprising that we found no such children in our cohort of children attending language units. Consequently, there were 5 common subgroups of children (again, the terminology in parenthesis is that of Rapin and Allen): our Cluster 1 (lexical-syntactic deficit syndrome), our Cluster 3 (verbal dyspraxia), our Cluster 4 (phonologic programming deficit syndrome), our Cluster 5 (phonological-syntactic deficit syndrome), and our Cluster 6 (semantic-pragmatic deficit syndrome). It is also important to point out that we are not in agreement with Rapin and Allen’s labelling of Cluster 3 as verbal dyspraxia. The conceptualization of verbal dyspraxia as a subgroup of SLI is not currently accepted. Verbal dyspraxia is considered a motor speech disorder rather than a language disorder, although expressive language scores may well be affected. Our Cluster 3 children had good naming vocabulary but were poor at all other tests used in the study. Furthermore, we find the labelling of different profiles of SLI as “deficit syndromes” problematic and prefer to describe the subgroups as different profiles of SLI.
Rapin (1996) furthered her classification work by proposing that the subgroups of children identified could be grouped together into three larger, clinical groupings. These subgroups or bands of impairment involved expressive language disorders (composed of verbal dyspraxia subgroup and phonological programming deficit syndrome; our Clusters 3 and 4), expressive-receptive language disorders (composed of verbal auditory agnosia and phonologic-syntactic deficit syndrome; our Cluster 5 only), and higher order processing disorders (composed of lexical-syntactic deficit syndrome and semantic-pragmatic deficit syndrome; our Clusters 1 and 6). Our five clusters were grouped into three broader subgroups or bands of impairment, following Rapin’s procedure. For this stage of the analysis, the following terminology was used to refer to these bands of impairment: expressive SLI, expressive/receptive SLI, and complex SLI, partially following Rapin. Where the present terminology differs is in the naming of the third band. Rapin suggests the term higher order processing disorders for this group of children, whereas the present study refers to these children as having complex SLI. The dissatisfaction with the term higher order processing disorder comes from the fact that none of the tests used in this study examined higher order processes per se. Furthermore, there is no consensus in the literature that the children in question have as a common underlying problem difficulties in higher order processing (Bishop, 1997). Finally, this group of children was composed of children who had lexical, syntactic, semantic, and pragmatic difficulties in the absence of phonological disorders, hence the choice of the term complex SLI to describe the extent of these children’s problems.
Stability of Rapin’s (1996) Banding: Test Score Patterns and Children’s Classification
Table 6 presents band means and 95% confidence intervals for Time 1 and Time 2. There appeared to be a very good match between Time 1 and Time 2 profiles of difficulties with no statistically significant differences between 5/6 test means for expressive SLI and complex SLI, and 4/6 test means for expressive/receptive SLI. This suggests that the classification of children into bands of impairment delineated similar profiles of difficulties at Time 1 and Time 2.
Band percentile means and 95% CI for Time1 and Time 2.
Table 6.Band percentile means and 95% CI for Time1 and Time 2.
Bands Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
Time 1
E-SLI 32.6
25.7 to 39.5
18.9
13.8 to 24.1
51.1
45.1 to 57.1
13.7
9.7 to 17.8
18.1
13.5 to 22.6
27.3
20.9 to 33.6
ER-SLI 9.4
7.2 to 11.5
8.6
6.2 to 19.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
Complex-SLI 20.6
16.7 to 24.5
11.6
9.3 to 13.9
38.8
33.1 to 44.5
31.5
25.2 to 37.8
78.7
74.2 to 83.22
16.6
13.5 to 19.6
Time 2
E-SLI 35.2
29.3 to 41.0
18.9
13.7 to 24.2
55.1
48.4 to 61.8
2.3
9.4 to 15.2
32.6
25.7 to 39.5
30.1
23.2 to 37.2
ER-SLI 11.7
8.6 to 14.9
7.3
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
Complex-SLI 18.6
13.7 to 23.5
7.7
4.9 to 10.6
41.1
34.1 to 48.1
33.9
24.9 to 42.9
75.2
68.0 to 23.5
15.9
11.5 to 20.4
Table 6.Band percentile means and 95% CI for Time1 and Time 2.
Bands Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
Time 1
E-SLI 32.6
25.7 to 39.5
18.9
13.8 to 24.1
51.1
45.1 to 57.1
13.7
9.7 to 17.8
18.1
13.5 to 22.6
27.3
20.9 to 33.6
ER-SLI 9.4
7.2 to 11.5
8.6
6.2 to 19.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
Complex-SLI 20.6
16.7 to 24.5
11.6
9.3 to 13.9
38.8
33.1 to 44.5
31.5
25.2 to 37.8
78.7
74.2 to 83.22
16.6
13.5 to 19.6
Time 2
E-SLI 35.2
29.3 to 41.0
18.9
13.7 to 24.2
55.1
48.4 to 61.8
2.3
9.4 to 15.2
32.6
25.7 to 39.5
30.1
23.2 to 37.2
ER-SLI 11.7
8.6 to 14.9
7.3
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
Complex-SLI 18.6
13.7 to 23.5
7.7
4.9 to 10.6
41.1
34.1 to 48.1
33.9
24.9 to 42.9
75.2
68.0 to 23.5
15.9
11.5 to 20.4
×
Table 7 presents the results for the stability of children’s classification into the three bands of impairment. Sixty-five percent of children stayed within the same band from Time 1 to Time 2, Kappa = 0.46, 95% confidence intervals = 0.35 to 0.58. Examination of these data showed almost complete overlap between the confidence intervals of this stability kappa (0.35 to 0.58), and the stability kappa obtained for the classification involving the six subgroups of children (0.34 to 0.51).
Cluster based classification of children into bands: stability from Time 1 to Time 2.
Table 7.Cluster based classification of children into bands: stability from Time 1 to Time 2.
Time 1
Expressive Expressive/
Receptive
Complex
Expressive 25 13 9
Time 2 Expressive/
Receptive
12 51 9
Complex 3 11 31
Table 7.Cluster based classification of children into bands: stability from Time 1 to Time 2.
Time 1
Expressive Expressive/
Receptive
Complex
Expressive 25 13 9
Time 2 Expressive/
Receptive
12 51 9
Complex 3 11 31
×
Overall, the above data suggest that no matter which classification system is used, the stability levels obtained are similar. Both systems delineate stable patterns of difficulties across time and both systems are remarkably unstable in the classification of children with SLI from one year to the next.
Discussion
Main Findings of the Study
The present investigation found considerable stability from Time 1 to Time 2 in the patterns of difficulties (as evidenced by test scores) delineated by the Conti-Ramsden, Crutchley, and Botting classification system (1997). In contrast, subgroup membership stability was poorer with 45% of the children moving across subgroups from Time 1 to Time 2. Examination of the movement of children across subgroups revealed that the moves represented substantial and real clinical changes in profile that could not be explained solely in terms of measurement error.
In addition, the stability of the proposed classification system, both in terms of patterns of difficulties and membership of a subgroup, was very similar to that found when children were classified into three subgroups following another well-known system (Rapin, 1996). Both classification systems produced stable patterns of difficulties across time and both systems were noticeably unstable in the classification of individual children from Time 1 to Time 2. In this sense, the Rapin (1996) classification system did not provide any added information that was not already available in the classification system proposed by Conti-Ramsden, Crutchley, and Botting (1997). The Rapin (1996) classification system is simply a less specific, broader classification system into three subgroups for the clinical population of children with SLI.
The Stability of Language Impairment Subtypes
The present investigation has demonstrated that movement across subgroups of language impairment is not simply a consequence of test error. The picture that emerges is both interesting and complex: profiles of difficulties in language impairment are stable even though individual children may be moving across subgroups. Why might this be the case?
SLI is not a unitary, static condition but a dynamic difficulty that evolves with developmental time (Conti-Ramsden & Adams, 1995; Miller, 1996). Thus, it is possible that, as signs of SLI change with time for individual children, the relations among those signs retain some predictability resulting in those signs covarying in a limited number of ways. In the present investigation, a clustering technique was used. The clustering technique assigns children to subgroups taking into consideration the performance of the children on all the six measures used in the study. Having said this, in the present investigation two signs or areas of difficulty appeared to be particularly involved in individuals changing across subgroups from one year to the next, that is, phonology and vocabulary (see Table 4). When changes occurred and children moved to a different subgroup, the profiles of such children became similar to the profiles of children belonging to another subgroup. Consequently, although children moved across subgroups, patterns of difficulties remained stable. For example, children who moved from Cluster 5 (all areas of language affected) to Cluster 3 (good naming vocabulary but poor on all other tests used) were children who improved significantly in their expressive vocabulary. These children no longer had problems across all areas of language like other children in Cluster 5. Now these children had problems across all language areas except for expressive vocabulary. Interestingly, there was already a cluster of children who had exactly those characteristics (i.e., Cluster 3). To reiterate, what is interesting about these findings is that changes in children’s linguistic profiles did not produce a whole new set of subgroups, instead, children’s profiles of difficulties continued to fall into a limited number of patterns already observed at Time 1.
The exception to the above was Cluster 2—children who appeared to be performing within the normal range and arguably should not be included in the classification of children with SLI. Nonetheless, Cluster 2 children may well be a group of children whose language difficulties have resolved by the time they participated in the study (age 7 at Time 1). This interpretation is supported by the work of Bishop and Edmundson (1987). These investigators found that approximately 37% of children who were found to have SLI at the preschool age of 4 years no longer presented with SLI at 5;6 years; that is, they appeared to have recovered. Following this line of argument, it is expected that a proportion of children with SLI may no longer present with SLI profiles at later ages. In the present investigation the percentage of children with SLI who appeared to have recovered (Cluster 2 children) was 7% at Time 1 (7 years) and 12 % at Time 2 (8 years).
Thus, patterns of language strengths and weaknesses change with developmental time and no doubt with the influence of other important factors such as intervention. What is interesting is that it appears that there are only a limited number of profiles of language strengths and weaknesses in children with SLI. In the present study, five such patterns of strengths and weaknesses have been identified in children with SLI who are 7 to 8 years of age (excluding Cluster 2, “normal” group children, as discussed earlier). In the following discussion, the five patterns of difficulties will be described without naming the clusters. As noted previously, Rapin and Allen’s (1987) terminology is problematic. It is thought premature to identify in a definite manner the clusters found in this study with Rapin and Allen’s (1987) terminology. With this in mind, the profiles of the children in this study are described.
Cluster 1 children are children with SLI who have difficulties with comprehension of grammar, word reading, and retelling a story in the context of good phonology and adequate expressive vocabulary. Cluster 3 children are children who have problems with comprehension of grammar, word reading, phonology, and retelling a story in the context of good expressive vocabulary. Cluster 4 children were very similar to Cluster 3 children except that their scores were better across the tests used, and their expressive vocabulary was not as good as that of children in Cluster 3. Cluster 5 children performed poorly on all the tests used and appeared to have difficulties across all areas of language. Finally, Cluster 6 children had difficulties retelling a story in the context of good phonology, good expressive vocabulary, good word reading, and adequate comprehension of grammar. These children’s difficulties were mainly evident at the discourse level when they were required to retell a story.
It also needs to be noted that, in any classification exercise, the resulting subgroups are necessarily dependent on the measures used in the investigation and the psychometric properties of the measurement instruments used. This is particularly relevant in two ways. First, the specificity of measurement within certain language construct domains necessarily restricts our ability to test discrete constructs such as “semantics,” “syntax,” or “pragmatics.” For example, it is hard to measure pragmatics, and current tests may collapse across many dimensions of syntax. Second, detection of stability may be obscured by psychometric properties of measurement. For example, relatively small changes in the Goldman-Fristoe Test can result, at certain ages, in large changes in percentile performance. Nonetheless, it is also important to emphasise that the five identified patterns or subgroups of SLI are based on a study that has a number of strengths. The present investigation involved a large sample of children (N = 242) which represented a random sample of 50% of all 7-year-olds attending language units in England. Although there are advantages to studies with methodologies that specify a priori and in detail the criteria used for selecting subjects as belonging (or not) to SLI, the reverse also has its own advantages. In this investigation, a large cohort of children receiving speech-language services in language units were identified and then the question “what sorts of problems do these children have?” was asked. In addition, the study was uniform in terms of age (7 years at Time 1 and 8 years at Time 2). This is a major methodological advantage because developmental effects and changes are not confounded in the classification system. Most previous studies (Miller, 1996; Rapin & Allen, 1987; Wilson & Risucci, 1986) have had mixed age groups; therefore developmental and age related changes were confounded.
Concluding Remarks
The results of the present investigation lend further weight to the argument that children with SLI fall into distinct subgroups. The present investigation also adds an important caveat to the argument. Although profiles of language strengths and weaknesses in the form of distinct subgroups appear to be stable over time, individual children’s language strengths and weaknesses change with time. Consequently, a large proportion of children move to different subgroups resulting in poor membership stability from one year to the next (for children aged 7 and 8 years). Thus, it appears that SLI is a dynamic condition that changes with developmental time and very likely with the influence of other important factors such as intervention. At present, we are in the process of seeing these children again at the age of 11 years. With this longer time scale, it may be possible for future research to begin to provide some information on patterns of change and development of different subgroups of children with SLI.
Acknowledgments
The authors gratefully acknowledge the support of the Nuffield Foundation for Grant AT251 [OD], Educational Transitions of Language-Impaired Children. We would also like to thank Alison Crutchley for help with data collection, Dr. Brian Faragher for statistical advice, and the schools and language units who gave their time and facilities for our assessments.
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Figure 1.

Cluster Profiles for Time 1 and Time 2

Cluster Profiles for Time 1 and Time 2
Figure 1.

Cluster Profiles for Time 1 and Time 2

×
Table 1.Cluster percentile means and 95% confidence intervals for Time 1.
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 52 15.6
11.8 to 19.5
9.9
7.3 to 12.6
32.4
25.8 to 39.0
14.8
11.3 to 18.3
78.9
74.2 to 83.6
15.2
11.7 to 18.7
2   n = 16 40.0
27.8 to 52.2
50.9
36.9 to 65.0
54.7
45.7 to 63.6
28.2
20.2 to 36.2
64.9
52.8 to 77.0
52.3
41.2 to 63.4
3   n = 29 15.1
10.3 to 19.9
12.7
7.4 to 18.1
62.7
57.5 to 67.8
11.3
6.3 to 16.3
14.1
8.9 to 19.2
14.6
8.2 to 20.9
4   n = 23 54.7
47.0 to 62.3
26.8
18.0 to 34.5
36.6
27.3 to 45.8
16.8
9.9 to 23.8
23.1
15.1 to 31.1
43.3
34.8 to 51.7
5   n = 84 9.4
7.2 to 11.5
8.6
6.2 to 10.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
6   n = 25 30.8
22.7 to 38.8
14.9
10.3 to 19.5
52.0
42.5 to 61.5
66.3
60.0 to 72.6
78.4
68.1 to 88.7
19.4
13.1 to 25.7
Table 1.Cluster percentile means and 95% confidence intervals for Time 1.
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 52 15.6
11.8 to 19.5
9.9
7.3 to 12.6
32.4
25.8 to 39.0
14.8
11.3 to 18.3
78.9
74.2 to 83.6
15.2
11.7 to 18.7
2   n = 16 40.0
27.8 to 52.2
50.9
36.9 to 65.0
54.7
45.7 to 63.6
28.2
20.2 to 36.2
64.9
52.8 to 77.0
52.3
41.2 to 63.4
3   n = 29 15.1
10.3 to 19.9
12.7
7.4 to 18.1
62.7
57.5 to 67.8
11.3
6.3 to 16.3
14.1
8.9 to 19.2
14.6
8.2 to 20.9
4   n = 23 54.7
47.0 to 62.3
26.8
18.0 to 34.5
36.6
27.3 to 45.8
16.8
9.9 to 23.8
23.1
15.1 to 31.1
43.3
34.8 to 51.7
5   n = 84 9.4
7.2 to 11.5
8.6
6.2 to 10.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
6   n = 25 30.8
22.7 to 38.8
14.9
10.3 to 19.5
52.0
42.5 to 61.5
66.3
60.0 to 72.6
78.4
68.1 to 88.7
19.4
13.1 to 25.7
Table 2.Cluster percentile means and 95% confidence intervals for Time 2 new cluster analysis (n = 207 children).
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 30 13.7
9.2 to 18.2
3.5
2.0 to 5.0
33.8
26.6 to 41.0
12.9
8.0 to 17.9
84.0
77.8 to 90.3
14.3
8.7 to 19.8
2   n = 25 58.0
48.9 to 67.1
19.3
12.5 to 26.1
75.8
69.3 to 82.5
39.4
29.1 to 35.3
87.5
79.5 to 95.6
39.4
30.5 to 48.3
3   n = 38 30.7
15.3 to 32.2
17.4
10.5 to 24.4
69.7
65.1 to 74.3
12.0
8.2 to 15.8
21.5
16.4 to 26.6
17.7
11.3 to 24.2
4   n = 19 44.2
33.4 to 54.8
21.8
13.8 to 29.7
26.0
18.4 to 33.6
12.9
8.2 to 17.5
54.8
41.0 to 68.7
55.1
45.7 to 64.6
5   n = 77 11.7
8.6 to 14.9
7.2
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
6   n = 18 26.8
16.5 to 37.0
14.7
8.6 to 20.9
53.2
39.8 to 66.5
68.7
60.2 to 77.3
60.3
46.0 to 74.6
18.8
10.8 to 26.
Table 2.Cluster percentile means and 95% confidence intervals for Time 2 new cluster analysis (n = 207 children).
Cluster Group Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
1   n = 30 13.7
9.2 to 18.2
3.5
2.0 to 5.0
33.8
26.6 to 41.0
12.9
8.0 to 17.9
84.0
77.8 to 90.3
14.3
8.7 to 19.8
2   n = 25 58.0
48.9 to 67.1
19.3
12.5 to 26.1
75.8
69.3 to 82.5
39.4
29.1 to 35.3
87.5
79.5 to 95.6
39.4
30.5 to 48.3
3   n = 38 30.7
15.3 to 32.2
17.4
10.5 to 24.4
69.7
65.1 to 74.3
12.0
8.2 to 15.8
21.5
16.4 to 26.6
17.7
11.3 to 24.2
4   n = 19 44.2
33.4 to 54.8
21.8
13.8 to 29.7
26.0
18.4 to 33.6
12.9
8.2 to 17.5
54.8
41.0 to 68.7
55.1
45.7 to 64.6
5   n = 77 11.7
8.6 to 14.9
7.2
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
6   n = 18 26.8
16.5 to 37.0
14.7
8.6 to 20.9
53.2
39.8 to 66.5
68.7
60.2 to 77.3
60.3
46.0 to 74.6
18.8
10.8 to 26.
Table 3.Movement of children across clusters from Time 1 to Time 2 (n = 201 children).
Time 2 clusters
cluster 1 cluster 2 cluster 3 cluster 4 cluster 5 cluster 6
cluster 1 18 3 4 5 8 3
cluster 2 8 3 4 1
Time 1 cluster 3 1 15 10
clusters cluster 4 1 6 4 8 2 1
cluster 5 9 11 2 51 2
cluster 6 1 8 1 11
Table 3.Movement of children across clusters from Time 1 to Time 2 (n = 201 children).
Time 2 clusters
cluster 1 cluster 2 cluster 3 cluster 4 cluster 5 cluster 6
cluster 1 18 3 4 5 8 3
cluster 2 8 3 4 1
Time 1 cluster 3 1 15 10
clusters cluster 4 1 6 4 8 2 1
cluster 5 9 11 2 51 2
cluster 6 1 8 1 11
×
Table 4.Change of test score in movement groups.
Movement group (n) Test of interest Minimum change Maximum change Mean change (SD)
1 to 5 (8) GF-Articulation* –22 percentiles –66 percentiles –41 (13) percentiles
3 to 5 (10) BAS Naming V* –6 percentiles –37 percentiles –24 (12) percentiles
5 to 1 (9) GF-Articulation* +23 percentiles +91 percentiles +55 (28) percentiles
BAS Naming V –2 percentiles +57 percentiles +20 (19) percentiles
5 to 3 (11) BAS Naming V* +14 percentiles +67 percentiles +45 (18) percentiles
6 to 2 (8) GF-Articulation* +0 percentiles +59 percentiles +9 (21) percentiles
BAS Naming V –3 percentiles +46 percentiles +18 (19) percentiles
Bus Story –20 percentiles +62 percentiles +27 (26) percentiles
TROG –13 percentiles +65 percentiles +20 (24) percentiles
Table 4.Change of test score in movement groups.
Movement group (n) Test of interest Minimum change Maximum change Mean change (SD)
1 to 5 (8) GF-Articulation* –22 percentiles –66 percentiles –41 (13) percentiles
3 to 5 (10) BAS Naming V* –6 percentiles –37 percentiles –24 (12) percentiles
5 to 1 (9) GF-Articulation* +23 percentiles +91 percentiles +55 (28) percentiles
BAS Naming V –2 percentiles +57 percentiles +20 (19) percentiles
5 to 3 (11) BAS Naming V* +14 percentiles +67 percentiles +45 (18) percentiles
6 to 2 (8) GF-Articulation* +0 percentiles +59 percentiles +9 (21) percentiles
BAS Naming V –3 percentiles +46 percentiles +18 (19) percentiles
Bus Story –20 percentiles +62 percentiles +27 (26) percentiles
TROG –13 percentiles +65 percentiles +20 (24) percentiles
Table 5.Whole cohort changes on tests.
Test Minimum change Maximum change Mean change (SD)
GF-Articulation –66 percentiles +92 percentiles +3 (26) percentiles
BAS Naming Vocabulary –60 percentiles +81 percentiles +9 (24) percentiles
BAS Word Reading –41 percentiles +95 percentiles –0.5 (12) percentiles
BAS Number Skills –48 percentiles +70 percentiles –2 (12) percentiles
Bus Story –58 percentiles +63 percentiles +3 (17) percentiles
TROG –40 percentiles +65 percentiles +5 (18) percentiles
Table 5.Whole cohort changes on tests.
Test Minimum change Maximum change Mean change (SD)
GF-Articulation –66 percentiles +92 percentiles +3 (26) percentiles
BAS Naming Vocabulary –60 percentiles +81 percentiles +9 (24) percentiles
BAS Word Reading –41 percentiles +95 percentiles –0.5 (12) percentiles
BAS Number Skills –48 percentiles +70 percentiles –2 (12) percentiles
Bus Story –58 percentiles +63 percentiles +3 (17) percentiles
TROG –40 percentiles +65 percentiles +5 (18) percentiles
×
Table 6.Band percentile means and 95% CI for Time1 and Time 2.
Bands Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
Time 1
E-SLI 32.6
25.7 to 39.5
18.9
13.8 to 24.1
51.1
45.1 to 57.1
13.7
9.7 to 17.8
18.1
13.5 to 22.6
27.3
20.9 to 33.6
ER-SLI 9.4
7.2 to 11.5
8.6
6.2 to 19.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
Complex-SLI 20.6
16.7 to 24.5
11.6
9.3 to 13.9
38.8
33.1 to 44.5
31.5
25.2 to 37.8
78.7
74.2 to 83.22
16.6
13.5 to 19.6
Time 2
E-SLI 35.2
29.3 to 41.0
18.9
13.7 to 24.2
55.1
48.4 to 61.8
2.3
9.4 to 15.2
32.6
25.7 to 39.5
30.1
23.2 to 37.2
ER-SLI 11.7
8.6 to 14.9
7.3
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
Complex-SLI 18.6
13.7 to 23.5
7.7
4.9 to 10.6
41.1
34.1 to 48.1
33.9
24.9 to 42.9
75.2
68.0 to 23.5
15.9
11.5 to 20.4
Table 6.Band percentile means and 95% CI for Time1 and Time 2.
Bands Test for Reception of Grammar BAS Number Skills BAS Naming Vocabulary BAS Word Reading Goldman Fristoe Test of Articulation Renfrew Bus Story
Time 1
E-SLI 32.6
25.7 to 39.5
18.9
13.8 to 24.1
51.1
45.1 to 57.1
13.7
9.7 to 17.8
18.1
13.5 to 22.6
27.3
20.9 to 33.6
ER-SLI 9.4
7.2 to 11.5
8.6
6.2 to 19.9
11.7
9.6 to 13.8
11.2
8.3 to 14.2
19.0
15.7 to 22.3
8.7
6.9 to 10.5
Complex-SLI 20.6
16.7 to 24.5
11.6
9.3 to 13.9
38.8
33.1 to 44.5
31.5
25.2 to 37.8
78.7
74.2 to 83.22
16.6
13.5 to 19.6
Time 2
E-SLI 35.2
29.3 to 41.0
18.9
13.7 to 24.2
55.1
48.4 to 61.8
2.3
9.4 to 15.2
32.6
25.7 to 39.5
30.1
23.2 to 37.2
ER-SLI 11.7
8.6 to 14.9
7.3
5.0 to 9.6
20.2
16.6 to 23.8
7.7
5.5 to 9.8
16.0
12.9 to 19.0
8.3
6.4 to 10.3
Complex-SLI 18.6
13.7 to 23.5
7.7
4.9 to 10.6
41.1
34.1 to 48.1
33.9
24.9 to 42.9
75.2
68.0 to 23.5
15.9
11.5 to 20.4
×
Table 7.Cluster based classification of children into bands: stability from Time 1 to Time 2.
Time 1
Expressive Expressive/
Receptive
Complex
Expressive 25 13 9
Time 2 Expressive/
Receptive
12 51 9
Complex 3 11 31
Table 7.Cluster based classification of children into bands: stability from Time 1 to Time 2.
Time 1
Expressive Expressive/
Receptive
Complex
Expressive 25 13 9
Time 2 Expressive/
Receptive
12 51 9
Complex 3 11 31
×