JCPSLP VOL 15 No 1 March 2013

point, each divided by number of utterances selected) at pre-intervention, post-intervention, and 3 months post- intervention. A significant time X group multivariate effect was predicted for each MANOVA, with the intervention groups outperforming the control group. Planned follow-up tests to the MANOVA were completed using mixed model Analyses of variance (ANOVAs) tests with adjusted alphas for each test (.05 divided by 2 = p < .025 for the DSS and MLU ANOVAs; .05 divided by 3 = p <.017 for each DSS grammatical category ANOVA). Post hoc analyses to the ANOVAs, also with adjusted alpha levels, were completed using univariate ANOVAs. These represented simple main effect tests for DSS and MLU scores for each of the three gain periods ( p = .025 divided by 3, p <.008) and the DSS grammatical categories at each of the three assessment time-points ( p = .017 divided by 3, p <.006). The adjusted alpha levels represented a Bonferroni correction, controlling for Type 1 error (Portney & Watkins, 2009). Results DSS and MLU gains The MANOVA revealed significant differences among groups on DSS and MLU change scores (dependent variables), Wilks’ V = .40, F (4,60) = 8.62, p < .001, N 2 = .37. A significant multivariate effect was found for time (3-month gain1, 3-month gain2, and 6-month gain), Wilks’ V = .32, F (4,28) = 15.07, p < .001, N 2 = .68. A significant interaction for group X time was also found, Wilks’ V = .37, F (8,56) = 4.55, p < .001, N 2 = .50. ANOVAs testing the dependent variables, using the pre-set adjusted alpha levels ( p < .025), were conducted as follow-up tests. There was a significant interaction effect for group X time for DSS, F (4,62) = 6.37, p < .001, N p 2 = .29, and MLU, F (4,62) = 3.26, p = .017, N p 2 = .17, change scores. Simple main effect tests were completed as a follow-up to the significant interaction for each ANOVA. Findings for DSS and MLU change met the set significance level ( p < .008) for follow-up tests for each gain period. Pairwise comparisons of means revealed that computer-assisted and table-top intervention resulted in significantly higher DSS and MLU gains compared to controls. Only the two intervention groups achieved DSS point gains at or above 0.76 for each gain period, demonstrating accelerated growth. The two interventions did not differ statistically for DSS or MLU ( p > .05). See figures 1 and 2.

3.5 3 2.5 2 1.5 1 0.5 0 -0.5 MLU point gain

computer-assisted table-top no-intervention

Pre-post (3-mth gain1)

Post-3 months post (3-mth gain2)

Pre-3 months post (6-mth gain)

Time points

DSS per cent error rates The MANOVA revealed significant differences among groups on personal pronoun , main verb , and sentence point , Wilks’ V = .39, F (6,58) = 5.85, p < .001, N 2 = .39. A significant multivariate effect was found for time (pre- intervention, post-intervention, 3 months post-intervention), Wilks’ V = .57, F (6,26) = 3.34, p = .005, N 2 = .44. A significant interaction for group X time was also found, Wilks’ V = .30, F (12,52) = 3.52, p < .001, N 2 = .45. Follow-up tests using ANOVAs on the dependent variables Figure 2. Mean MLU performance for each group Note. MLU = Mean Length of Utterance (Brown, 1973; Miller, 1981).

computer-assisted table-top no-intervention

20 15 10

5 0 -5 Per cent error rate

PP pre-intervention PP post-intervention PP 3-month post Time points

computer-assisted table-top no-intervention

60 50 40 30 20 10 0 Per cent error rate

4

computer-assisted table-top no-intervention

MV pre-intervention MV post-intervention MV 3-month post Time points

3

computer-assisted table-top no-intervention

2

80 70 60 50 40 30 20 10 0 Per cent error rate

1

0

DSS point gains

-1

SP pre-intervention SP post-intervention SP 3-month post Time points

Pre-post (3-mth gain1)

Post-3 months post (3-mth gain2)

Pre-3 months post (6-mth gain)

-2

Figure 3. Mean per cent error rates for DSS grammatical categories per group at each assessment time point Note. DSS = Developmental Sentence Scoring (Lee, 1974); PP = personal pronoun; MV = main verb; SP = sentence point

Time points

Figure 1. Mean DSS performance for each group Note. DSS = Developmental Sentence Scoring (Lee, 1974).

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JCPSLP Volume 15, Number 1 2013

Journal of Clinical Practice in Speech-Language Pathology