R: Combine p-values using the sum of p method also known as...

sump {metap} | R Documentation

## Combine p-values using the sum of p method also known as Edgington's method

### Description

Combine p-values using the sum p method

### Usage

    sump(p)
    ## S3 method for class 'sump'
    print(x, ...)

### Arguments

`p` | A vector of p-values
`x` | An object of class ‘`sump`’
`...` | Other arguments to be passed through

### Details

Defined as

((sum p) ^ k) / k! - (k-1)C1 ((sum p - 1) ^ k) / k! + (k-2)C2 ((sum p - 2) ^ k) / k!

where there are k studies and the series continues until the numerator becomes negative.

Some authors use a simpler version ((sum p) ^ k) / k! where there are k studies but this can be very conservative when sum p > 1. There seems no particular need to use this method but it is returned as the value of `conservativep` for use in checking published values.

The values of p should be such that 0<=p<=1 and a warning is given if this is not true. An error is given if possibly as a result of removing them fewer than two valid p values remain. A warning is given when the internal calculations are likely to have been subject to numerical error and an alternative method should be used to check the result.

The plot method for class ‘`metap`’ calls `schweder` on the valid p-values

### Value

An object of class ‘`sump`’ and ‘`metap`’, a list with entries

`p` | The transformed sum of the p-values
`conservativep` | See details
`validp` | The input vector with illegal values removed

### Author(s)

Michael Dewey

### References

Becker, B J. Combining significance levels. In Cooper, H and Hedges, L V, editors A handbook of research synthesis, chapter 15, pages 215–230. Russell Sage, New York, 1994.

Edgington, E S. An additive method for combining probability values from independent experiments. Journal of Psychology, 80:351-363, 1972.

### See Also

See also `schweder`

### Examples

    data(edgington)
    sump(edgington) # p = 0.097

[Package metap version 0.8 Index]