Sample size calculation: Survival analysis (logrank test)
Calculates the required sample size for the comparison of survival rates in two independent groups.
You are interested in detecting a difference between survival rates of 0.6 and 0.4. You plan to have twice as many cases in the first group as in the second group.
For α-level you select 0.05 and for β-level you select 0.20 (power is 80%).
Enter the values 0.6 and 0.4 for the Survival rates in Group 1 and Group 2, and enter 2 for the Ratio of sample sizes.
After you click the Calculate button the program displays the required sample size.
In the example 129 cases are required in Group 1 and 65 cases in Group 2, giving a total of 194 cases.
A table shows the required total sample size for different Type I and Type II Error levels.