Computes the sample size required to estimate a tetrachoric correlation with desired confidence interval precision. Set the tetrachoric planning value to the smallest value within a plausible range for a conservatively large sample size.
size.ci.tetra(alpha, p1, p2, cor, w)
Returns the required sample size
alpha level for 1 - alpha confidence
planning value for row 1 marginal proportion
planning value for column 1 marginal proportion
tetrachoric planning value
desired confidence interval width
Bonett2005statpsych
size.ci.tetra(.05, .4, .3, .5, .3)
# Should return:
# Sample size
# 296
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