## EXAMPLE 1 (from Chow S, Shao J, Wang H 2008, p. 61 - 62):
## A pharmaceutical company is interested in conducting a clinical trial
## to compare two cholesterol lowering agents for treatment of patients with
## congestive heart disease using a parallel design. The primary efficacy
## parameter is the LDL. In what follows, we will consider the situation
## where the intended trial is for testing non-inferiority of mean responses
## in LDL. Assume that 80% power is required at a 5% level of significance.
## In this example we assume a -0.05 unit change in LDL is a clinically
## meaningful difference. Assume the standard deviation of LDL is 0.10 units
## and the LDL concentration in the treatment group is 0.20 units and the
## LDL concentration in the control group is 0.20 units.
epi.ssninfc(treat = 0.20, control = 0.20, sigma = 0.10, delta = 0.05, n = NA,
power = 0.80, r = 1, nfractional = FALSE, alpha = 0.05)
## A total of 100 subjects need to be enrolled in the trial, 50 in the
## treatment group and 50 in the control group.
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