Martine van der Pluijm

169 General discussion analyzing the results of the design] . Researchers planned strict procedures within a limited period and requested time, allowing no customization. Teachers and parents perceived this part as the least inspiring and sometimes over-demanding. For them, this part of the research did not visibly contribute to relationships or better practices, leading to less intrinsic motivation for investing time to participate in data collection activities. During the last round of interviews, teachers reported that the data collection for the research was a burden. Interestingly, when the interviewer asked whether teachers would participate again in a same type of research (i.e., including the three objectives of DBR), most teachers responded positively because of the surplus value for improving their work. One more disadvantage of the DBR approach is that the focus on the needs of stakeholders minimizes the opportunities to investigate the generalizability of the design. The small scale of this research, the prevalent conditions (e.g., urban context, selection of teachers who were motivated), and the absence of a control condition limit the generalizability of the results. Therefore, this thesis is an exploration. Experimental research may provide further insight into the generalizability of the design principles (Edelson, 2006; Yin, 2003). Such experimental research should allow the program to be adapted to the specific needs of diverse contexts and populations (i.e., rural areas, and families and teachers from different backgrounds) (e.g., Plomp, 2009; Reeves, 2006). Doing so, researchers can build on latest approaches of program fidelity, acknowledging the complexity of balancing between program fidelity and program adaptation (e.g., Durlak & DuPre, 2008; Powell & Carey, 2012). In this manner, DBR and experimental research may work complementarily in their objectives to find effective solutions, allowing for program adaptations according to the needs of the specific contexts (Cordray & Pion, 2006). LIMITATIONS AND SUGGESTIONS FOR FURTHER RESEARCH The studies conducted for this thesis have limitations that lead to suggestions for further research. We discuss three limitations and suggestions for future research. Child language and literacy development One of the limitations of this thesis is that we did not study child language outcomes. We only reviewed interventions on their effect on children’s oral language development (Chapter 2) and measured teachers’impressions about child language development and child participation (Chapter 4). For future studies on the use of AHL with lower-educated parents, we recommend that measures for children’s oral language development are administered in pretests and posttests to assess effects.