Summary statistics to include; can be a scalar value or a vector (for multiple summary statistics at once).
Possible choices are:
nsim, the number of replications with non-missing point estimates and standard error.
thetamean, average point estimate.
thetamedian, median point estimate.
se2mean, average standard error.
se2median, median standard error.
bias, bias in point estimate.
rbias, relative (to the true value) bias in point estimate.
empse, empirical standard error.
mse, mean squared error.
relprec, percentage gain in precision relative to the reference method.
modelse, model-based standard error.
relerror, relative percentage error in standard error.
cover, coverage of a nominal level\
becover, bias corrected coverage of a nominal level\
power, power of a (1 - level)\
Defaults to NULL, in which case all possible summary statistics are included.