sample sizes

  1. A

    Sample Size calculation - "difference in mean differences"

    We have two independent patient groups in an Individual RCT ("treatment" and control["standard care"]). The treatments will result in a change of scores on a psychometric scale, from baseline to end-line. A baseline assessment was conducted using this scale, and thereafter, the participants were...
  2. J

    Statistical comparisons for large sample sizes (n>1000)

    I am comparing the drug exposures across two different groups, consisting of 1000 simulated drug exposures per group. Drug exposures are continuous variables following a normal distribution. I want to know if different doses yield a statistically significant difference in mean drug exposure...
  3. S

    sample size

    Hi everyone, I do my research to see the association of 2 qualitative variables which make 2x3 contingency table. I calculate the required sample size by using G*Power. I got 964 of the total sample size from G*Power. The problem is my population size have just 330. What should I do? For...
  4. W

    comparing test results obtained on the basis of different sample sizes

    I have variables a1 and a2 with 57 observations each, and variables b1 and b2 with 29 observations each. I compare a1 with a2 by means of a paired-samples t-test, this gives p<0.001. Next, I compare b1 with b2 by means of a paired-samples t-test, this gives p>0.05 (actually p>0.10). I compared...
  5. L

    Methodology for Sample sizes for surveys to multiple branches of a credit union

    Hi, I am reviewing the methodology for sample sizes for surveys that are mailed out to credit union members on a monthly basis. Please forgive me for not using proper formulas. Any advice is appreciated. Total population is 57,200 members, but not all members perform transactions each...