Page 82 - Second language development of newly arrived migrant kindergarteners - Frederike Groothoff

82 Chapter 4 Table 4.4: Fit of Different Models (-2LL) for Changes in PPVT score (168 cases) with Addition of Months of Exposure to Dutch at School (EDS) as Explanatory Variable. Model PPVT4: β0ijcons + β1ij Age1ijb + β2Age2ij PPVT7: PPVT4 + β3EDSij PPVT8: PPVT7 + β4Age*EDSij -2LL Models 1377.92 1353.21 PPVT4 vs PPVT7 1303.04 PPVT7 vs PPVT8 Comparison ΔΧ2 Δdf 24.71 1 50.17 1 p <.001 <.001 In Figure 4.3 the general development for pupils with different amounts of Exposure to Dutch at School is presented. Figure 4.3 might be difficult to interpret since Exposure to Dutch at School and Age are related: every month a child grows older it also has had more exposure to Dutch. However, there was a fixed main effect of Exposure to Dutch at School. Overall, pupils with a larger Exposure to Dutch at School had higher PPVT scores, indicated by the solid black line. Furthermore there was an interaction effect between Age and Exposure to Dutch at School, which means that the relation between Age and PPVT scores differs per amount of Exposure (see Table 1 in Appendix 1 for the estimated parameters). The negative interaction between Age and Exposure to Dutch at School means that the effect of Exposure to Dutch is larger for younger pupils than for older pupils. In Figure 4.3 the general development of PPVT with Exposure to Dutch as explanatory variable for pupils with different ages is presented (see Table 1 in Appendix 1 for the estimated parameters). There was a fixed main effect of Exposure to Dutch at School and an interaction effect between Age and Exposure to Dutch at School. Therefore, all lines in Figure 4.3 show an increase (remember that when pupils grew older, their Exposure to Dutch also increased one month), however, since the effect of Exposure is smaller for older pupils, the striped and dotted line for the oldest pupils shows less difference with the solid black line (the hypothetical 0 Exposure line) compared to the lines of the youngest and average aged pupils.