| sump {metap} | R Documentation |
Combine p-values using the sum of p (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 significance values |
x |
An object of class ‘ |
... |
Other arguments to be passed through |
Details
Defined as \[\frac{(\sum_{i=1}^k p_i)^k}{k!} - {k \choose 1}\frac{(\sum_{i=1}^k p_i - 1)^k}{k!} + {k \choose 2}\frac{(\sum_{i=1}^k p_i - 2)^k}{k!} ...\] where there are \(k\) studies and the series continues until the numerator becomes negative (Edgington 1972).
Some authors use a simpler version
\[\frac{(\sum_{i=1}^k p_i)^k}{k!}\]
but this can be very conservative when
\(\sum_{i=1}^k p_i > 1\).
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 \(p_i\) should be such that \(0\le p_i\le 1\) and a warning is given if that is not true. A warning is given if, possibly as a result of removing illegal values, fewer than two values remain and the return values are set to NA. 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 plotp 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
Edgington ES (1972). “An additive method for combining probability values from independent experiments.” Journal of Psychology, 80, 351–363.
See Also
See also plotp
Examples
data(dat.metap)
edgington <- dat.metap$edgington
sump(edgington) # p = 0.097