convert_ma | R Documentation |
Takes a meta-analysis class object of d values or correlations (classes r_as_r
, d_as_d
, r_as_d
, and d_as_r
; second-order meta-analyses are currently not supported) as an input and uses conversion formulas and Taylor series approximations to convert effect sizes and variance estimates, respectively.
convert_ma(ma_obj, ...) convert_meta(ma_obj, ...)
ma_obj |
A meta-analysis object of class |
... |
Additional arguments. |
The formula used to convert correlations to d values is:
(sqrt(1 / (p * (1-p))) * r) / sqrt(1 - r^2)
The formula used to convert d values to correlations is:
d / sqrt(1 / (p * (1-p)) + d^2)
To approximate the variance of correlations from the variance of d values, the function computes:
var_r ~= a_d^2 * var_d
where a_d is the first partial derivative of the d-to-r transformation with respect to d:
a_d = -1 / ((d^2 * (p - 1) * p - 1) * sqrt(d^2 + 1 / (p - p^2)))
To approximate the variance of d values from the variance of correlations, the function computes:
var_d ~= a_r^2 * var_r
where a_r is the first partial derivative of the r-to-d transformation with respect to r:
a_r = sqrt(1 / (p - p^2)) / (1 - r^2)^1.5
A meta-analysis converted to the d value metric (if ma_obj was a meta-analysis in the correlation metric) or converted to the correlation metric (if ma_obj was a meta-analysis in the d value metric).
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