For statistical inference about the mean of a single population when the population standard deviation is unknown,the degrees for freedom for the t-distribution equal n − 1 because we lose one degree of freedom by using the:
A)sample mean as an estimate of the population mean.
B)sample standard deviation as an estimate of the population standard deviation.
C)sample proportion as an estimate of the population proportion.
D)sample size as an estimate of the population size.

Question

Quizplus · Accepted Answer

We lose one degree of freedom by using the sample mean as an estimate of the population mean because the sample mean is a random variable that varies from sample to sample. The degrees of freedom for the t-distribution are therefore n - 1, where n is the sample size.

For Statistical Inference About the Mean of a Single Population