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METAL has the ability to apply a genomic control correction to all input files. METAL will estimate the inflation of the test statistic by comparing the median test statistic to that expected by chance, and then apply the genomic control correction to the p-values (for SAMPLESIZE weighted meta-analysis) or the standard error (for STDERR weighted meta-analysis). This should only be applied to files with whole genome data (i.e. should not be used for settings where results are only available for a candidate locus or a small number of SNPs selected for follow-up of [[GWAS]] results). Genomic control settings can be customized for each input file. We recommend applying genomic control correction to all input files that include genomewide data and, in addition, to the meta-analysis results. To apply genomic control to the meta-analysis results, just perform an initial meta-analysis and then load the initial set of results into METAL to get final, genomic control adjusted results.
METAL has the ability to apply a genomic control correction to all input files. METAL will estimate the inflation of the test statistic by comparing the median test statistic to that expected by chance, and then apply the genomic control correction to the p-values (for SAMPLESIZE weighted meta-analysis) or the standard error (for STDERR weighted meta-analysis). This should only be applied to files with whole genome data (i.e. should not be used for settings where results are only available for a candidate locus or a small number of SNPs selected for follow-up of [[GWAS]] results). Genomic control settings can be customized for each input file. We recommend applying genomic control correction to all input files that include genomewide data and, in addition, to the meta-analysis results. To apply genomic control to the meta-analysis results, just perform an initial meta-analysis and then load the initial set of results into METAL to get final, genomic control adjusted results.
=== Sample Overlap Correction ===
Correction for sample overlap in sample size weighted meta-analysis (developed by Sebanti Sengupta and implemented by Daniel Taliun).
First, METAL estimates the number of individuals that are common among two or more studies based on Z-statistics from each study. Then, METAL adjusts for sample overlap when calculating overall Z-statistics by correcting the weights with the estimated number of individuals in common.
To enable correction for sample overlap in your sample size weighted meta-analysis, use OVERLAP ON command (valid only with SCHEME SAMPLESIZE). By default, METAL uses Z-statistics <1 for esimating the number of individuals that are common among studies. To change this threshold, use ZCUTOFF [number] command.
Details on the method can be found in [[media:METAL_sample_overlap_2017-11-15.pptx|these slides]], and eventually as a manuscript (est. 2018).
=== Strand Information ===
=== Strand Information ===
