Chapter 9 Mastery Quiz

Question 1

Is it necessary to correct for error when calculating the standard error for a t test? Explain your answer.

Answer 1

No; we already corrected the standard deviation and are now reflecting the size of the sample.

Question 2

What is one benefit of increasing the sample size when using t distributions?

Answer 2

Larger sample sizes reflect the parameters of the population more closely.

Question 3

When there is uncertainty about the parameters of a population we are interested in studying, we use a t distribution instead of a z distribution. Is the t distribution wider or thinner than the z distribution and why?

Answer 3

The t distribution is wider because we are less certain of the findings compared to the z distribution.

Question 4

Standard error is used in the calculation of both the z and t statistic, with the difference that:

Answer 4

the standard error for the t statistic is estimated using the sample standard deviation.

Question 5

The correct formula for Cohen’s d for a single-sample t test is:

Answer 5

(M – µ)/s.

Question 6

A dot plot graphs all the data in a sample, with the range of scores along the ________ and a dot for each data point above the corresponding value.

Answer 6

x-axis

Question 7

You are comparing two groups. You know the population mean from which the samples come, but you do not know the population standard deviation. Should you use a t test or a z test?

Answer 7

t test; you must estimate the standard deviation for the population

Question 8

The symbol df stands for:

Answer 8

degrees of freedom.

Question 9

“Degrees of freedom” refers to what on a t table for a single-sample t test?

Answer 9

number of scores that are free to vary in estimating population parameters, N – 1