The "1way" in the npar1way procedure refers to the existence of one factor, in this case, the treatment, but not to one sample. In this case we have two independent sample (placebo and real drug), so, npar1way can do analysis in case of three or more treatments like drug A, drug B and Placebo. To test one sample I use the proc univariate, like in this example: data test; do sample = 1 to 10; y = 3+normal(8); output; end; run; proc univariate data=test mu0=3 normal plot; var y; run; These comand tests the hypotesis of a true mean equals to three. Three tests are presented in the results: Student t test (parametric) and two non-parametric tests: Signed Rank Test (Wilcoxon test to one sample) and sign test. The "normal" option bring normality tests to help us to choose the more appropriate test. If normality assumption is reasonable, t test must be chosen, if not, a non-parametric test can be more appropriate. Signed Rank test (Wilcoxon) can be considered if we have skewness coefficient between -2 and +2, but not normality. Otherwise, Sign test must be considered when the data are not normally distributed and have asymmetric behaviour. An special case is the test of paired data, when we calculate the difference between two values observed in dependent conditions like in the left hand and in the right hand of a person, each one treated with one product, for example. It is common to test the mean of the differences is equal to zero (mu0=0).
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