Type the R call and key output for the one-sided Welch test of the current billing system (n = 12, mean 31.2, sd 9.5) against the new one (n = 10, mean 24.1, sd 6.8).
Type the R call and key output for the one-sided Welch test of the current billing system (n = 12, mean 31.2, sd 9.5) against the new one (n = 10, mean 24.1, sd 6.8).
Answer
> t.test(current, new, alternative = "greater") t = 2.0373, df = 19.62, p-value = 0.02767 alternative hypothesis: true difference in means is greater than 0 sample estimates: mean of x mean of y 31.2 24.1
Default t.test(x, y) is Welch. df = 19.62 is Satterthwaite, not the hand min(11, 9) = 9; the same t = 2.037 gives p = 0.0277 on the larger df — inside the hand bracket 0.025 < p < 0.05 and smaller than the 0.0360 it would be on 9 df.
BCc ch 5 (software printouts); H-W9 (Case 1 / Case 2) — shape only; R output from a live Rscript session; original dataset