lod2p: Convert a LOD score to a P-value.

In drmjc/mjcstats: MJC's general statistics library

Description

The simple interpretation of a LOD score is the log of the odds, ie 3 means 1:1000 odds. Simple conversion to P is just 10^-lod ie lod 3 becomes 0.001

Accoring to Peirce2006 p646:
convert lrs2p via p = 10^-(LRS/4.6); where 4.6 = 2 ln(10)
and lod = LRS/4.6
thus p = 10^-lod

Usage

  lod2p(lod, df = 1)

Arguments

lod	a numeric vector of LOD scores
df	degrees of freedom

Details

The more accurate method of converting LRS scores to Pvalues is to transform them to chisquared variables, you need to know the degrees of freedom (number of different genotypes - 1; ie df=1 for inbred mice, df=2 for outbred SNPs, df= >2 for microsat alleles). Remember, chi sq distributions are defined only by the degrees of freedom (http://en.wikipedia.org/wiki/Chi-square_distribution).

Value

a numeric vector of p-values

Author(s)

Mark Cowley, 20/9/07

References

http://dx.doi.org/10.1007/s00335-005-0187-8

Examples

lod2p(lrs2lod(24.3))
# [1] 5.29e-06
lrs2p( 5.28*2*log(10), 2)
# [1] 5.25e-06

drmjc/mjcstats documentation built on May 15, 2019, 2:41 p.m.