Unlike mass-univariate analyses, SVM takes inter-regional correlations into account, and provides numerical indicators for group membership without multiple comparison biases [Orrù et al., 2012].
Studies evaluating the effects of acute exposure to air pollution are subject to multiple comparisons bias because the associations are often assessed with multiple pollutants (e.g. SO2, NO2, CO, O3, PM10, and PM2.5) and different exposure periods (e.g. same day, 1-day lag, and cumulative day averages).
Alternatively, some AHS findings may have occurred by chance because of the large number of multiple comparisons or bias from uncontrolled confounding or other source of bias.
Important causes of non-replication include inadequate statistical power to detect small and moderate effects, phenotype heterogeneity, population stratification, publication bias, and multiple comparison testing.
After performing Bonferroni correction to eliminate bias of multiple comparison, we found that the frequency of the rs1801270 A allele in cases (0.421) was statistically significantly lower than that found in controls (0.494; p = 0.003).
From their perspective, I imagine that complaints about multiple comparisons and selection bias would fall into the category of "technicalities". But, y'know, if you want to play the game you gotta follow the rules.
Multiple comparisons did not bias the statistical results presented here (p<0.001).
The studies have several limitations related to the quality of the exposure assessment, small numbers of exposed cases, multiple comparisons, and possible bias toward the reporting of positive results.
