Comment on the paper entitled "PLAY Project Home Consultation intervention program for young children with autism spectrum disorders: A randomized controlled trial

Response to van Ginkel and Kroonenberg

In our paper we indicated that “the field has not advanced to provide methods for addressing repeated measures ANOVA analysis” and cited van Ginkel and Kroonenberg (2014). It should be clarified that this refers to van Ginkel and Kroonberg (2014)’s assertion that “the implementation of the combination rules needed for ANOVA in statistical software packages has either been quite limited or very well hidden.” It should also be clarified that van Ginkel and Kroonberg (2014) have proposed methods to conduct the analyses using additional macros and explanations not integrated into major statistical software packages and argue for the inclusion in future upgrades. As van Ginkel and Kroonenberg (2014) state: “To date, the implementation of the combination rules needed for ANOVA in statistical software packages has either been quite limited or very well hidden. SPSS 19.0 does not provide any pooled results for F tests for multiply imputed data. Using an SPSS macro (Van Ginkel, 2010a) the procedure may be carried out in SPSS but this still requires substantial manual preprocessing. For repeated-measures ANOVA the procedure is even more complicated. Although SAS 9.3 and Stata 10.0 have a procedure for carrying out the combination rules for ANOVA in Multiple imputation, the manual provides no clear practical guidance in how to use them in the specific context of ANOVA. The procedure outlined in this article should also be of assistance to any SAS or Stata user who intends to use Multiple imputation in this context. In the appendix, it is explained how exactly the procedures can be carried out in SAS 9.3, Stata 10.0, and SPSS 19.0 using Van Ginkel's (2010a) macro. Considering the involved task needed to actually carry out the described procedure, its implementation in future releases of SPSS and other software packages, as well as a clear guidance with examples in the SAS and Stata manuals, seems desirable if its use is to become commonplace.”