The Sample Size Samba . The problem with sample size calculation is that you often get the inverse square law working twice over. Say an investigator comes along and says "We expect pain score to ...

So the formula I use is (sample/600) ^ 0.5. e.g. the poll’s sample size, ... Its sample size, subject to the calculation I described above. 2. Its pollster reliability rating. 3.

Table 1 below shows that if the groups are of equal size (a 1:1 ratio), then the power is 0.87. The study has an 87% chance of detecting a true difference in birth weight of 250g. The power reduces as ...

Summary Choosing the proper sample size for an investigation is one of the crucial jobs required of a statistician. Regardless of whether the statistician is deciding the number of patients to select ...

Woolson, Bean, and Rojas (1986, Biometrics 42, 927-932) present a simple approximation of sample size for Cochran's (1954, Biometrics 10, 417-451) test for detecting association between exposure and ...