Performing A One-Sample T-Test

  1. Performing a One-Sample t-Test

The data in STAT1.NormTemp come from an article in the Journal of Statistics Education by Dr. Allen L. Shoemaker from the Psychology Department at Calvin College. The data are based on an article in a 1992 edition of JAMA (Journal of the American Medical Association), which questions
the notion that the true mean body temperature is 98.6. There are 65 males and 65 females. There
is also some question about whether mean body temperatures for women are the same as for men. The variables in the data set are as follows:

ID                    Identification number

BodyTemp      Body temperature (degrees Fahrenheit)

Gender            Coded (Male, Female)

HeartRate       Heart rate (beats per minute)

  1. Look at the distribution of the continuous variables in the data set using PROC UNIVARIATE, including producing histograms and insets with means, standard deviations and sample size.
    1. Perform a one-sample t-test to determine whether the mean of body temperatures (the variable BodyTemp in STAT1.NormTemp) is 98.6. Produce a confidence interval plot of BodyTemp with the value 98.6 used as a reference.
      1. What is the value of the t statistic and the corresponding p-value?
      1. Do you reject or fail to reject the null hypothesis at the 0.05 level that the average temperature

  2. Using PROC T-TEST for Comparing Groups

Elli Sagerman, a Masters of Education candidate in German Education at the University of North Carolina at Chapel Hill in 2000, collected data for a study. She looked at the effectiveness of a new type of foreign language teaching technique on grammar skills. She selected 30 students to receive tutoring; 15 received the new type of training during the tutorials and 15 received standard tutoring. Two students moved away from the district before completing the study. Scores on a standardized German grammar test were recorded immediately before the 12-week tutorials and then again
12 weeks later at the end of the trial. Sagerman wanted to see the effect of the new technique on grammar skills. The data are in the STAT1.GERMAN data set.

Change          Change in grammar test scores

Group            The assigned treatment, coded Treatment and Control

Analyze the data using PROC TTEST. Assess whether the treatment group improved more than
the control group.

  1. Do the two groups appear to be approximately normally distributed?
    1. Do the two groups have approximately equal variances?
    1. Does the new teaching technique seem to result in significantly different change scores compared with the standard technique?