ci.biphi {statpsych} | R Documentation |
Computes a confidence interval for a population biserial-phi correlation using a transformation of a confidence interval for an odds ratio with .5 added to each cell frequency. This measure of association assumes the group variable is naturally dichotomous and the response variable is artificially dichotomous.
ci.biphi(alpha, f1, f2, n1, n2)
alpha |
alpha level for 1-alpha confidence |
f1 |
number of participants in group 1 who have the attribute |
f2 |
number of participants in group 2 who have the attribute |
n1 |
sample size for group 1 |
n2 |
sample size for group 2 |
Returns a 1-row matrix. The columns are:
Estimate - estimate of biserial-phi correlation
SE - standard error
LL - lower limit of the confidence interval
UL - upper limit of the confidence interval
Ulrich R, Wirtz M (2004). “On the correlation of a naturally and an artificially dichotomized variable.” British Journal of Mathematical and Statistical Psychology, 57(2), 235–251. ISSN 00071102, doi:10.1348/0007110042307203.
ci.biphi(.05, 46, 15, 100, 100)
# Should return:
# Estimate SE LL UL
# 0.4145733 0.07551281 0.2508866 0.546141