Although violations of the assumptions of parametric statistical procedures suggested that non-parametric analysis would, in this instance, be a more appropriate indicator of treatment outcome, a lack of non-parametric alternatives to the ANOVA meant that parametric options were necessary.
Batch effects were minimized using COMBAT [27] with the non-parametric option, floored at 0.00001, and log2 transformed.
Differences across groups regarding migraine disability (MIDAS), depression (PHQ) and neck disability (NDI) were calculated using the Mann-Whitney-U test as a non-parametric option for not normally distributed data [29]).
As is typical of parametric/non-parametric contrasts, the potential difficulty with the non-parametric option is loss of power.
Furthermore, the net benefit regression framework features parametric and non-parametric options to characterise uncertainty in the cost-effectiveness analysis data.
To evaluate the metabolite variation across different experimental groups, XCMS Online provides the univariate analysis of variance (one-way ANOVA) as a parametric test option and the Kruskal Wallis test as its nonparametric alternative.
This was performed using the parametric test option with a false discovery rate of P < 0.01.
Two-way ANOVA was performed in GeneSpring using the parametric test option with a false discovery rate of P < 0.01 or P < 0.05, and assuming variances to be equal.
However, where a natural transformation is available to make an outcome 'more normal', undertaking the analysis on the transformed scale using normal test statistics is usually a more efficient and powerful option than the non-parametric alternative.
Global uptake differences between brain scans were adjusted using the "proportional scaling" statistical parametric mapping (SPM) option.
