(This article was first published on

**ALSTAT R Blog**, and kindly contributed to R-bloggers)The recovery time (in days) is measured for 10 patients taking a new drug and for 10 different patients taking a placebo. We wish to test the hypothesis that the mean recovery time for patients taking the drug is less than for those taking placebo. The data are:

Placebo: 15,14,12,8,14,7,16,10,15,12

A. Perform a hypothesis testing under an assumption of normality and equal population variances.

*Solution:*

Codes:

B. Perform a hypothesis testing under an assumption of normality and unequal population variances.

*Solution:*

Codes: (Using the defined data above)

Interpretation: Still, we lack the evidence to reject the null hypothesis at p = 0.3006, and so the true difference in mean recovery time for patients taking the drug is either equal to or greater than those taking a placebo.

To

**leave a comment**for the author, please follow the link and comment on his blog:**ALSTAT R Blog**.R-bloggers.com offers

**daily e-mail updates**about R news and tutorials on topics such as: visualization (ggplot2, Boxplots, maps, animation), programming (RStudio, Sweave, LaTeX, SQL, Eclipse, git, hadoop, Web Scraping) statistics (regression, PCA, time series, trading) and more...