\begin{Schunk}
\begin{Sinput}
 ## Set a variety of factors and compare p-values
 
 ## We need to choose levels of our predictors (sample size and SD)
 ## - equal v. unequal group sample sizes
 ## - equal v. unequal group variances
 ## - mean-difference: 0, 5, or 10
 cond.N <- c("30:30", "40:20")
 cond.SD <- c("10:20", "15:15", "20:10")
 cond.M <- c("100:100") # for now, mean-difference = 0
 ## A fully crossed design runs all combinations of these levels.  This
 ## is a 2 (N) by 3 (SD) factorial design, so it has 2 * 3 = 6
 ## conditions
 conds <- expand.grid(maxReps = 3, SD = cond.SD, N = cond.N, M = cond.M,
                       stringsAsFactors = FALSE)
 head(conds)
\end{Sinput}
\begin{Soutput}
  maxReps    SD     N       M
1       3 10:20 30:30 100:100
2       3 15:15 30:30 100:100
3       3 20:10 30:30 100:100
4       3 10:20 40:20 100:100
5       3 15:15 40:20 100:100
6       3 20:10 40:20 100:100
\end{Soutput}
\end{Schunk}
