2.15. Statistical Analysis
SECONDARY
The sample size for the ANCOVA was according to Cohen’s approach [Cohen suggested that d = 0.2 is to be considered a ‘small’ effect size, with 0.5 representing a ‘medium’ effect size and 0.8 representing a ‘large’ effect size. This means that, if the difference between two groups’ means is less than 0.2 standard deviations, the difference is negligible, even if it is statistically significant.For the calculation of the sample sizes, we chose:α = 0.05; β = 0.20; d = 0.25; St Dev ANCOVA > 3.These values suggest, for 1 – β ≈ 0.80, the use of N = 150 total patients.Subgroup analyses were conducted on subjects with a total cholesterol (TC) reduction of >10% and a body weight reduction of ≥5% using the exact chi-square analysis (Fisher test) to determine the differences between groups.The results will be presented as ITT (intention-to-treat) and PP (per-protocol) values.For the final evaluation, only the PP values will be considered.Primary endpoint analysis: the change in weight at the end of the clinical investigation was carried out by the analysis of covariance, adjusting the means of the final values by basal means. The mean difference was reported, with a corresponding SE.For the secondary endpoints on a continuous scale, the comparison between the intervention groups were approached by the analysis of covariance, adjusting the means of the final values by basal means. The mean difference was reported, with a corresponding standard error. For the baseline values of the comparison in the PP and ITT groups, the ANOVA and Wilcoxon rank sum tests were used.For the secondary endpoints on the frequencies (the proportion of subjects who improved the intensity of the care profile), the chi-square test and Fisher’s exact test were used. The same analysis was applied for the PP and ITT groups. The missing values were estimated for all subjects undergoing the treatment. The random sampling procedure was adopted: the missing value was replaced by a value extracted randomly from those available for the respective group.The SAS Institute’s JMP14 Pro 2019 software was used for the analysis.