nct_sample_size         Main trial sample size using the non-central
                        t-distribution
optimized_nct_sample_size
                        Optimize pilot sample size using the
                        non-central t-distribution
optimized_ucl_sample_size
                        Optimized pilot sample size using the UCL
                        method
plot.sspilot            Plot pilot and main-trial sample size
                        relationship
standard_sample_size    Standard sample size for a two-arm continuous
                        outcome trial
ucl_sample_size         Main trial sample size using the upper
                        confidence limit method
