Page 172 - Second language development of newly arrived migrant kindergarteners - Frederike Groothoff

172 Chapter 8 125 115 105 95 85 75 65 55 45 35 25 Growth PPVT Within 80% - Within 80% + Between 80% - Between 80% + Age in Months Figure 8.1: Graphical Representation of the General Development Model of PPVT (118 cases) with 80% Reliability. Figure 8.1 shows that the effect of Age on PPVT scores is significant. The differences within individuals (represented by the striped lines in Figure 8.1) also depend on Age; we can give a more precise estimate of the vocabulary development for older pupils as compared to younger pupils. The analysis will now continue with the new General Development Model, PPVTc. The two significant variables of CLASS namely, Positive Climate and Regard for Student Perspectives, were first added to this new General Development Model. A likelihood ratio test showed that the main effect of Positive Climate did not contribute significantly to the fit of the model of the observed data (PPVTf). However, the model fit increased when the interaction between Age and Positive Climate (ΔΧ2 (PPVTg) = 3.86; df = 1; p = .05; See Table 8.2) was included. Table 8.2: Fit of Different Polynomials (-2LL) for Changes in PPVT score (118 cases) with the Addition of Positive Climate (PosCli) as Explanatory Variable. Comparison -2LL Models ΔΧ2 Δdf p 0.15 1 .70ns 3.86 1 .050 Model PPVTc: β0ijcons + β1i Age1ij + 917.77 β2Age2ij PPVTf: PPVTc + β2PosCliij PPVTg: PPVTf + β3Age*PosCliij 917.61 PPVTc vs PPVT f 913.76 PPVTf vs PPVT g 48 52 56 60 64 68 72 76 80 84 88 92 96 100 104 PPVT score