Question

A local tennis pro-shop strings tennis rackets at the tension (pounds per square inch) requested by the customer. Recently a customer made a claim that the pro-shop consistently strings rackets at lower tensions, on average, than requested. To support this claim, the customer asked the pro shop to string 20 new rackets at 59 psi. Upon receiving the rackets, the customer measured the tension of each and calculated the following summary statistics: x = 58 psi, s = 3.7 psi. In order to conduct the test, the customer selected a significance level of a = .01. Interpret this value.
A) There is a 1% chance that the sample will be biased.
B) The smallest value of a that you can use and still reject H0 is .01.
C) The probability of making a Type II error is .99.
D) The probability of concluding that the true mean is less than 59 psi when in fact it is equal to 59 psi is only .01.

Answer 1

The answer is D. Alpha is the probability of making a type 1 error and D is the definition of alpha.