In implementing our software for meta-analysis, a primary consideration was to facilitate identification and resolution of common problems in meta-analysis. A secondary consideration was the ability to specify custom headers and delimiters so as to combine input files with varying formats generated from a variety of statistical packages. METAL tries to resolve or flag common problems that result from an inconsistent choice of allele labels or genomic strand across studies, or the presence of invalid P-values or test statistics at a subset of markers (due to numerical errors). METAL allows data to be filtered according to quality control measures, and can handle very large data sets (that typically total several GB in size) in workstations with a memory capacity not exceeding 2 GB.
