logitp: Combine p values using logit method

Description

Combine p values using logit method

Usage

logitp(p, log.p = FALSE)
# S3 method for logitp
print(x, ...)

Value

An object of class ‘logitp’ and

‘metap’, a list with entries

t: Value of Student's t
df: Associated degrees of freedom
p: Associated p-value
validp: The input vector with illegal values removed

Arguments

p: A vector of significance values
log.p: Logical, if TRUE result is returned as log(p)
x: An object of class ‘logitp’
...: Other arguments to be passed through

Author

Michael Dewey

Details

Defined as t = - _i=1^k p_i1 - p_iC t = - sum log(p / (1 - p)) / C where C = k ^2 (5 k + 2)3(5 k + 4)C = sqrt((k pi^2 (5 k + 2)) / (3(5 k + 4))) and k is the number of studies.

The values of p_i should be such that 0 < p_i < 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.

The plot method for class ‘metap’ calls plotp on the valid $p$ -values.

References

becker94metap

Examples

Run this code

data(dat.metap)
teachexpect <- dat.metap$teachexpect
logitp(teachexpect) # t = 2.763, df = 99, p = 0.0034, from Becker
beckerp <- dat.metap$beckerp
logitp(beckerp) # t = 1.62, df = 29, NS, from Becker
validity <- dat.metap$validity$p
logitp(validity) # t = 9.521, df = 104, p = 3.89 * 10^{-16}
all.equal(exp(logitp(validity, log.p = TRUE)$p), logitp(validity)$p)

Run the code above in your browser using DataLab

Get 50% off unlimited learning