GPA-class {GPA} | R Documentation

## Class "GPA"

### Description

This class represents GPA model fit.

### Details

When users use `fdr` method, users can specify the pattern using 1 and * in `pattern` argument, where 1 and * indicate phenotypes of interest and phenotypes that are not of interest, respectively. For example, when there are three phenotypes, `pattern="111"` means a SNP associated with all of three phenotypes, while `pattern="11*"` means a SNP associated with the first two phenotypes (i.e., association with the third phenotype is ignored (averaged out)).

### Objects from the Class

Objects can be created by calls of the form `new("GPA", ...)`.

### Slots

`fit`:

  Object of class `"list"`, representing the fitted GPA model.

`setting`:

  Object of class `"list"`, representing the setting for GPA model fitting.

`gwasPval`:

  Object of class `"matrix"`, representing the p-value matrix from GWAS data.

`annMat`:

  Object of class `"matrix"`, representing the annotation matrix.

### Methods

show

  `signature(object = "GPA")`: provide brief summary of the object.

print

  `signature(x = "GPA")`: provide the matrix of posterior probability that a SNP belongs to each combination of association status.

fdr

  `signature(object = "GPA", pattern=NULL)`: provide local FDR. By default (i.e., `pattern=NULL`), it returns a matrix of local FDR that a SNP is not associated with each phenotype (i.e., marginal FDR), where the order of columns is same as that in input GWAS data. If a pattern is specified, a vector of corresponding local FDR is provided. See the details about how users can specify the pattern.

cov

  `signature(object = "GPA", silent=FALSE, vDigitEst=1000, vDigitSE=1000 )`: provide the covariance matrix for parameter estimates of GPA model. If `silent=TRUE`, it suppresses the summary output. `vDigitEst` and `vDigitSE` control number of digits for reporting parameter estimates and standard errors. For example, setting it to 1000 means printing out values up to three digits below zero.

estimates

  `signature(object = "GPA")`: extract parameter estimates from GPA model fit.

se

  `signature(object = "GPA")`: extract standard errors for parameter estimates from GPA model fit.

### Author(s)

Dongjun Chung

### References

Chung D*, Yang C*, Li C, Gelernter J, and Zhao H (2014), "GPA: A statistical approach to prioritizing GWAS results by integrating pleiotropy information and annotation data," PLoS Genetics, 10: e1004787. (* joint first authors)

### See Also

`GPA`, `pTest`, `aTest`.

### Examples

    showClass("GPA")

    # simulator function

    simulator <- function( risk.ind, nsnp=20000, alpha=0.6 ) {

      m <- length(risk.ind)

      p.sig <- rbeta( m, alpha, 1 )
      pvec <- runif(nsnp)
      pvec[ risk.ind ] <- p.sig

      return(pvec)
    }

    # run simulation

    set.seed(12345)
    nsnp <- 1000
    alpha <- 0.3
    pmat <- matrix( NA, nsnp, 5 )

    pmat[,1] <- simulator( c(1:200), nsnp=nsnp, alpha=alpha )
    pmat[,2] <- simulator( c(51:250), nsnp=nsnp, alpha=alpha )
    pmat[,3] <- simulator( c(401:600), nsnp=nsnp, alpha=alpha )
    pmat[,4] <- simulator( c(451:750), nsnp=nsnp, alpha=alpha )
    pmat[,5] <- simulator( c(801:1000), nsnp=nsnp, alpha=alpha )

    ann <- rbinom(n = nrow(pmat), size = 1, prob = 0.15)
    ann <- as.matrix(ann,ncol = 1)

    fit.GPA.wAnn <- GPA( pmat, ann )
    fit.GPA.wAnn
    pp.GPA.wAnn <- print( fit.GPA.wAnn )
    fdr.GPA.wAnn <- fdr( fit.GPA.wAnn )
    fdr11.GPA.wAnn <- fdr( fit.GPA.wAnn, pattern="11" )
    fdr1..GPA.wAnn <- fdr( fit.GPA.wAnn, pattern="1*" )
    cov.GPA.wAnn <- cov( fit.GPA.wAnn )
    est.GPA.wAnn <- estimates( fit.GPA.wAnn )
    se.GPA.wAnn <- se( fit.GPA.wAnn )

[Package GPA version 1.4.0 Index]