Dr. John Rasp's Statistics Website

Review questions:

1) What is Student's t distribution? When is it used?

2) What assumptions must be made about the data for valid use of a Student's t test, in testing a null hypothesis concerning a population mean?

Computational exercises:

1) Applied Statistics major Gracetta Squornshellous has heard Dr. Rasp make many disparaging remarks about the University of Alabama. His latest comment ("having the brains of an intellectually challenged turnip") prompted her to ask the research question: Are Alabama students really dumber than the national average? In other words, she tests H0: μ=100 vs. HA: μ<100. She selects a random sample of five UofA students and gives them IQ tests. Their scores are as follows:

 104 88 95 103 90

Perform a Student's t test of Gracetta's hypotheses. (You make all necessary "niceness" assumptions.)

2) Give a 95% confidence interval for the population mean, for the situation in the previous exercise.

SOLUTIONS:
1) t = -1.22, 4 df, p-value = .145 (one-tailed)
2) 96 + 9.1