Chapter 8

Question 1

statistical hypothesis testing

Answer 1

A procedure that allows us to evaluate hypothesis about population parameters based on sample statistics.

Question 2

research hypothesis

Answer 2

A statement reflecting the substantive hypothesis. It is always expressed in terms of population parameters, but its specific form varies form test to test.

Question 3

one-tailed test

Answer 3

A type of hypothesis test that involves a directional research hypothesis. It specifies that the values of one group are either larger or smaller than some specified population value.

Question 4

right-tailed test

Answer 4

A one-tailed test in which the sample outcome is hypothesized to be at the right tail of the sampling distribution.

Question 5

left-tailed test

Answer 5

A one-tailed test in which the sample outcome is hypothesized to be at the left tail of the sampling distribution.

Question 6

two-tailed test

Answer 6

A type of hypothesis test that involves a nondirectional research hypothesis. We are equally interested in whether the values are less than or greater than one another. The sample outcome may be located at both the lower and the higher ends of the sampling distribution.

Question 7

null hypothesis

Answer 7

A statement of “no difference” that contradicts the research hypothesis and is always expressed in terms of population parameters.

Question 8

z statistic (obtained)

Answer 8

The test statistic computed by converting a sample statistic (such as the mean) to a Z score. The formula for obtaining Z varies from test to test.

Question 9

p value

Answer 9

The probability associated with the obtained value of Z.

Question 10

alpha

Answer 10

The level of probability at which the null hypothesis is rejected. It is customary to set alpha a the .05, .01, or .001 level.

Question 11

type I error

Answer 11

The probability associated with rejecting a null hypothesis when it is true.

Question 12

type II error

Answer 12

The probability associated with failing to reject a null hypothesis when it is false.

Question 13

t statistic (obtained)

Answer 13

The test statistic computed to test the null hypothesis about a population mean when the population standard deviation is unknown and is estimated using the sample standard deviation.

Question 14

t distribution

Answer 14

A family of curves, each determined by its degrees of freedom. It is used when the population standard deviation is unknown and the standard error is estimated from the sample standard deviation.

Question 15

degrees of freedom

Answer 15

The number of scores that are free to vary in calculating a statistic.

Question 16

sampling distribution of the difference between means

Answer 16

A theoretical probability distribution that would be obtained by calculating all the possible mean differences that would be obtained by drawing all the possible independent random samples of size N1 and N2 from two populations where N1 and N2 are both greater than 50.