Table 7. Two independent sample t-test vs. MANOVA p-values and effect sizes for VB-MAPP and ABLLS.

Cohen's d: Small effect size = 0.20; Medium effect size = 0.50; Large effect size = 0.80 or higher

Partial η² is equal to partial eta squared

Partial η²: Small effect size = 0.01; Medium effect size = 0.06; Large effect size = 0.14 or higher

MANOVA: Multivariate Analysis of Variance; VB-MAPP: Verbal Behavior Milestones Assessment and Placement Program; ABLLS: Assessment of Basic Language and Learning Skills-Revised

Dependent variable	Two independent sample t-test (p-value)	Two independent sample t-test effect size (Cohen's d)	MANOVA (p-value)	MANOVA effect size (partial η²)
VB-MAPPMandDiff	<0.001	-1.329	<0.001	0.297
VB-MAPPTactDiff	0.001	-1.241	0.001	0.269
VB-MAPPLRDiff	0.002	-1.176	0.002	0.248
VB-MAPPVPMTSDiff	0.002	1.207	0.002	0.258
VB-MAPPIndependentPlayDiff	0.003	-1.140	0.003	0.237
VB-MAPPSocialPlayDiff	<0.001	-1.361	<0.001	0.307
VB-MAPPMotorImitationDiff	0.002	-1.223	0.002	0.263
VB-MAPPECHOICDiff	<0.001	-1.652	<0.001	0.395
VB-MAPPSpontaneousVocalizationDiff	0.002	-1.208	0.002	0.259
VB-MAPPLRFFDiff	0.001	-1.242	0.001	0.269
VB-MAPPIntraverbalDiff	0.014	-0.928	0.014	0.171
VB-MAPPGroupBehaviorDiff	<0.001	-1.523	<0.001	0.357
VB-MAPPLinguisticStructureDiff	0.045	-0.743	0.045	0.117
VB-MAPPTotalDiff	<0.001	-1.942	<0.001	0.474
ABLLSReceptiveDIFF	0.390	-0.348	0.390	0.027
ABLLSRequestsDIFF	0.062	-0.773	0.062	0.119
ABLLSLabelingDIFF	0.505	-0.269	0.505	0.016
ABLLSIntraverbalDIFF	0.281	-0.438	0.281	0.041
ABLLSSpontaneousVocalizationDIFF	0.777	0.114	0.777	0.003
ABLLSSyntaxGrammarDIFF	0.287	-0.433	0.287	0.040
ABLLSSocialInteractionDIFF	0.135	-0.613	0.135	0.078
ABLLSGeneralizedRespondingDIFF	0.697	-0.157	0.697	0.006
ABLLSTotalDIFF	0.202	-0.520	0.202	0.057