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Fig. 2 | Annals of General Psychiatry

Fig. 2

From: Effect of fish oil omega-3 fatty acids on reduction of depressive symptoms among HIV-seropositive pregnant women: a randomized, double-blind controlled trial

Fig. 2

Quantile–quantile plot normality test for change in BDI-II scores by study arm The quantile–quantile plot normality statistical test for change in BDI-II depressive symptom scores conducted showed that the scores were normally distributed after 4 weeks: fish oil, N = 92; soybean oil, N = 98; and after 8 weeks: fish oil, N = 86; soybean oil—N = 96). Any variability present in the distribution of the scores in the samples was not statistically significant, based on Levene’s test of variance for sample means of the change in scores after 4 weeks (F (1188) = 0.79, p = 0.37; medians (F (1180) = 0.80, p = 0.37) and after 8 weeks (F (1180) = 1.96 p = 0.16); medians (F (1180) = 1.45, p = 0.23) and standard deviation test of variance (p = 0.24). Variability in errors across observations was controlled for through robust analysis method. Hence, the change in BDI-II depressive symptom scores met the regression analysis assumptions of normality

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