The test statistic t is created by taking the sample mean difference
and dividing by the standard error of the sample mean difference,
If the null hypothesis is true, this test statistic has a t distribution with
-1 degrees of freedom, where
is the number of pairs. For
Mackenzie’s 10 runners, the degrees of freedom will be 10 – 1 = 9.
Warm-Up: Check Your Understanding
Eight cars were run to determine their mileage, in miles per gallon (MPG). Then each car was given a tune-
up, and run again to measure the mileage a second time. The difference in mileage was computed as
difference = After MPG minus Before MPG. Assume that the selection of 8 cars represents a random
sample of cars.
Select the appropriate alternative hypothesis to assess if on average mileage significantly improves
after a tune up.
The researcher of course is hoping that the results of the experiment are statistically significant.
What type of
-value would the researcher want to obtain?
Lab Workbook Page 54