We present a simple sample-size formula for weighted log-rank statistics applied to clustered survival data with variable cluster sizes and arbitrary treatment assignments within clusters. This ...

This study discusses the sample size requirement for the Welch test in the one-way fixed-effect analysis of variance with unknown and possibly unequal variances. The authors propose a formula of ...

Statistical power and sample size are inextricably linked, with a positive correlation between power and sample size. An assortment of factors influences the power of a test including the sample size, ...

Given the unacceptable quality of the sample size calculation of COVID-19 trials, I strongly suggest that all research teams include a statistician or invite a statistician to evaluate the ...