Learning Check, Estimated variance and t

1. You don't estimate the population variance by using the sample variance directly because the sample variance

a. is usually unknown

b. is from the wrong population

c. tends to be too large

d. tends to be too small

2. Which of the following is true about __t __distributions?

a. There are 4 different __t __distributions.

b. For any given sample size, there are multiple __t
__distributions.

c. As sample size increases, the __t __distribution increasingly
resembles a normal curve.

d. __t __distributions are generally leptokurtic (light-tailed)

3. __t __scores are used instead of __Z __scores when

a. you choose a one-tailed test.

b. the population variance is unknown.

c. the sample size is less than than 30.

d. the mean for the comparison population is unknown

4. Difference scores are usually used with

a. a __t __test for a single sample.

b. a __t __test for dependent means.

c. a __t __test for independent means.

d. a __t __test for three or more samples.

***Answers below***

1. d

2. c

3. b

4. b