Returns the total number of observations required in a case control study. Uses the formulae on page 420 of Kirkwood and Sterne, 2nd Ed.
nice_sampsi_cc(pi_0, or, power, alpha, ratio = 1)Proportion of controls exposed (0-1)
Minimum odds ratio to be detected
The power required (0-100%)
The alpha to be detected (0-100%)
Ratio of controls to cases
It should be noted that there is an error on p422 that is corrected here: https://higheredbcs.wiley.com/legacy/college/kirkwood/0865428719/updates/updates.htm The error is in the last line of step 3, where the print states 2.2769/0.17^2 = 179.4 The correction is 2.2769^2/0.17^2 = 179.4
# Example 35.4, page 419 and 422 of Kirkwood and Sterne, 2nd Ed
# This gives a slightly lower result than Kirkwood and Sterne due to rounding.
nice_sampsi_cc(pi_0 = 0.4, or = 2, power = 90, alpha = 5)
#> [1] 354