Wim Gombert

118 CHAPTER 7 DESIGN AND ANALYSIS e SB and DUB groups formed the independent predictor variables in the current investigation. To assess oral pro ciency, the four subscales on the SOPA rating scale (oral uency, grammar, vocabulary and listening comprehension) were considered as continuous outcome variables. As a result, each participant received four scores and a total score, which was the sum of all four individual scores. e total scores as well as the scores on the four aspects of speaking were subsequently analyzed as ve dependent variables using a series of independent sample t-tests. All scores were inserted into SPSS (version 27) and t-test assumptions were checked. A boxplot showed that only data on the vocabulary aspect rendered outliers in both groups. e data for the total score showed a normal distribution but, upon close inspection, the data for all four aspects individually did not. Finally, all data, except those for the oral uency subtest, met the homogeneity of variance assumption. Based on the results of these assumption checks, a regular independent samples t-test (with the con dence interval set at 95%, p < .05) was conducted to analyze the total score but, for all four scores on subscales, a non-parametric Mann Whitney U test was used instead. In all cases, e ect sizes were calculated using the Cohen’s d statistic (Cohen, 1988); see Lenhard & Lenhard, 2016 for more details on this statistic as a measure of e ect size). Following the guidelines proposed by Plonsky and Oswald (2014), a measure of d > 0.8 constitutes a large e ect size. RESULTS Table 18 below presents the overall total scores on the SOPA test as a measure of L2 French oral pro ciency. As can be seen, a higher mean was obtained by the DUB as compared to the SB-taught group. As all assumptions were met pertaining to the overall scores, a parametric Independent Samples T-test was used to compare these mean scores, yielding a signi cant result (t(131) = 11,3, p < 001), with a very large e ect size d = 2.05. (Cohen, 1988). Table 18 provides details of this analysis. TABLE 18. Overall French l2 oral proficiency, split per teaching programs Total score on the SOPA test (max. score 36) SB program (N = 55) DUB program (N = 78) Cohen’s d Significance (2-tailed) Mean (SD) 18.2 (4.1) 26.5 (4.0) d = 2.05 p <.001