metap (version 1.1)

sump: 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 sump
print(x, ...)

Arguments

p

A vector of significance values

x

An object of class ‘sump’

...

Other arguments to be passed through

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

Details

Defined as $$\frac{(\sum _{i=1}^k{p}_i{)}^k}{k!}-(\genfrac{}{}{0ex}{}{k-1}{1})\frac{(\sum _{i=1}^k{p}_i-1{)}^k}{k!}+(\genfrac{}{}{0ex}{}{k-2}{2})\frac{(\sum _{i=1}^k{p}_i-2{)}^k}{k!}...$$ where there are $k$ studies and the series continues until the numerator becomes negative edgington72ametap.

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. An error is given if, possibly as a result of removing illegal values, fewer than two 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 plotp on the valid $p$-values.

References

See Also

See also plotp

Examples

# NOT RUN {
data(edgington)
sump(edgington) # p = 0.097
# }