Page 171 - Second language development of newly arrived migrant kindergarteners - Frederike Groothoff
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The influence of the school learning environment 171 A development model was build based on the 118 cases of PPVT scores, starting with only an intercept. From the comparison between the consecutive models (see Table 8.1) it is apparent that a model with a fixed linear component – allowing for differences in Age – fit the data better than a model with only an intercept (ΔΧ2 (PPVTb) = 82.84; df = 1; p < .001). The variance within individuals depends on the age of participants (ΔΧ2 (PPVTc) = 19.30; df = 1; p < .001). However, the between individuals variation did not depend on Age (PPVTd). Furthermore, adding Age2 to the model did not improve the fit (PPVTe). Table 6.1 in Appendix 6 shows the parameter estimates. Hence, in the final model (PPVTc) a fixed effect of Age, as well as a variance within pupils component which depends on Age needs to be included, and with this model we continued the analysis. Table 8.1: Fit of Different Polynomials (-2LL) for Changes in PPVT score (118 cases) as well as the Comparison of Consecutive Models. Model PPVTa: β0ijcons a       1019.91 Comparison -2LL Models ΔΧ2 Δdf 82.84 1 19.30 2 4.00 2 0.43 1 p <.001 <.001 .07ns .51ns               PPVTb: PPVTa + β1Age1ij PPVTc: PPVTb + e1ijAge1ij PPVTd: PPVTc + u10jAge1ij PPVTe: PPVTc + β2Age2ij 937.07 PPVTa vs PPVTb 917.77 PPVTb vs PPVTc 912.53 PPVTc vs PPVTd 917.43 PPVTcb vs PPVTe a In addition to the intercept, variance components for differences within and between individuals are estimated. b This model could not be estimated when u10j was included, therefore PPVTe is compared to model PPVTc. Based on this General Development Model we constructed Figure 8.1, in which both the average development as well as the differences within and between individuals are represented (see Table 6.1 in Appendix 6 for the parameter estimates). The average receptive vocabulary at an age of 72 months was estimated as 68.46. Each month a child grew older, his receptive vocabulary increased by 1.11.         


































































































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