2.2.2. Association of Meta-Analysis Method to Outcome Variable
The objective and type of outcome types (e.g., two-class, multi-class, survival) [24] will govern the choice of both the test statistic (t-statistic, F-statistic, log-rank statistic) and the meta-analysis method (combing p-values, effect sizes, or ranks). Methods combing effect sizes (standardized mean differences or odds ratios) are appropriate for combining two-class outcomes. Meta-analysis of expression studies with continuous outcomes (e.g., using regression or correlation coefficients) and survival outcomes (based on log-rank statistics) have typically been performed using combined p-values [50,55] and can be performed using the MetaDE package [37]. To capture concordant expression patterns for multi-class outcomes, Lu et al. [52] have applied multi-class correlation (min-MCC) because the F-statistic has been found to frequently fail to capture concordant patterns of gene expression.