Deck 14: The T-Test

Question 1

All t -Tests use the same t distribution regardless of the size of the sample and its standard deviation.

Answer 1

False

Question 2

It is appropriate to use the independent-samples t-Test when:

A)We want to compare the means of pairs of individuals who have been matched because they are similar to each other.
B)We want to compare the means of two independent groups.
C)We want to compare a sample statistic to a population statistic.
D)We want to compare the means of more than two groups.

Answer 2

We want to compare the means of two independent groups.

Question 3

Suppose an experiment compares two independent groups on an ordinal dependent variable.Which of the following is the most appropriate nonparametric statistical procedure

A)Mann-Whitney U test
B)Sign test
C)Wilcoxon matched-pairs test
D)t-test

Answer 3

Mann-Whitney U test

Question 4

How many degrees of freedom are there in a t-test for a study in which there are 50 clients in the experimental group and 40 clients in the control group?

A)90
B)88
C)45
D)2

Question 5

Randy wants to see whether Intervention A is more effective than Intervention B in improving self-esteem scores.Randy conducts an experiment to see if recipients of Intervention A improve more in self-esteem from pretest to posttest than recipients of Intervention B, using the .05 level of significance.Randy conducts two paired-sample t-Tests and finds a p value of .04 for Intervention A's improvement and a p value of .06 for Intervention B's improvement.Randy then conducts an independent-samples t-Test of the posttest scores and finds a p value of .55.Which of the following statements is an appropriate conclusion from Randy's findings?

A)Intervention A is more effective than Intervention B in improving self-esteem scores.
B)Both interventions are effective in improving self-esteem scores, but Intervention A is more effective.
C)Both interventions are equally effective in improving self-esteem scores.
D)We cannot conclude that either intervention is effective in improving self-esteem scores.

Question 6

The t-Test formula involves calculating a t-score by:

A)Dividing the difference between two means by the standard deviation of the experimental group.
B)Dividing the difference between two means by the standard error of the difference between means.
C)Dividing the difference between two means by the standard deviation of the control group.
D)Dividing the difference between two standard deviations by the difference between two means.

Question 7

The t -Test can be used with an interval or ratio level dependent variable and a dichotomous nominal independent variable.

Question 8

It is appropriate to use the t-Test when:

A)Comparing the means of two groups.
B)Comparing the means of two or more groups.
C)Comparing the means of three or more groups.
D)Both variables are at the ratio level of measurement.

Question 9

Suppose a study is done in which the experimental and control groups both get pretests and posttests.Which of the following is the best statistical procedure?

A)Conduct a paired-samples t-test separately for each group to see whether the experimental group's improvement is more statistically significant than the control group's improvement
B)Conduct an independent-samples t-test that compares the posttest means only.
C)Conduct an independent-samples t-test that compares the changes scores in the two groups.
D)All of these are equally acceptable.

Question 10

A t distribution will provide a better estimate of the population mean and standard error than will a z distribution when the sample size is very small or badly skewed.

Question 11

It is appropriate to use the one-sample t-Test when:

A)We want to compare the means of pairs of individuals who have been matched because they are similar to each other.
B)We want to compare the means of two independent groups.
C)We want to compare a sample statistic to a population statistic.
D)All of the variables are at the nominal level of measurement.

Question 12

Chris wants to test the significance of the difference in the number of treatment sessions attended by clients who have no connection to one another and who have been randomly assigned to either Group A and Group B.Chris should use:

A)The one-sample t-Test.
B)The paired-samples t-Test.
C)The independent-samples t-Test.
D)An independent-samples t-Test with change scores.

Question 13

It is appropriate to use the t-Test when:

A)The independent and dependent variables are both at the nominal level of measurement.
B)The independent and dependent variables are both at the ordinal level of measurement.
C)The independent and dependent variables are both at the ratio level of measurement.
D)The independent variable is nominal and dichotomous and the dependent variable is at the interval or ratio level of measurement.

Question 14

The t -Test calculates a t-score by dividing the difference between two means by the standard error of the difference between means in the theoretical sampling distribution.

Question 15

An independent samples t -Test with a sample size of 100 will have 2 degrees of freedom.

Question 16

In a pilot study, Dana wants to test the significance of the improvement in mean scores from pretest to posttest.Dana should use:

A)The one-sample t-Test.
B)The paired-samples t-Test.
C)The independent-samples t-Test.
D)An independent-samples t-Test with change scores.

Question 17

Which of the following statements is correct regarding the t distribution?

A)It will be flatter and more spread out with a small sample than with a large sample.
B)It will be flatter and more spread out with a small standard deviation than with a large standard deviation.
C)It will be flatter and more spread out with a large sample than with a small sample.
D)The more flatter and spread out it is, smaller difference between means are required for statistical significance.

Question 18

It is appropriate to use the paired-samples t-Test when:

A)We want to compare the means of pairs of individuals who have been matched because they are similar to each other.
B)We want to compare the means of two independent groups.
C)We want to compare a sample statistic to a population statistic.
D)We want to compare the means of more than two groups.

Question 19

When using an independent-samples t-Test, which of the following is considered when calculating the degrees of freedom?

A)The number of values that are free to vary in each group if we know the mean and sample size of each group.
B)The number of values we would need to know in each group in order to deduce the remaining values, in light of the mean and sample size of each group.
C)Each group's sample size minus 1.
D)When combining both groups, the overall sample size minus 2.
E)All of these.

Question 20

The term degrees of freedom refers to how many values are free to vary in a set of values if we know the summary statistic and the number of values in the set.

Question 21

The paired-samples t-Test is used when the two groups of values that we want to compare are connected or related to each other in some way.

Question 22

An independent samples t -Test with a sample size of 50 will have 48 degrees of freedom.

Question 23

The independent-samples t-Test is used when we want to compare the means of two independent groups.

Question 24

If one group has a significant change in a paired-samples t-Test, and another group does not in its (separate) paired-samples t-Test, that signifies a significant difference between the groups.

Question 25

A non-parametric alternative to the t -Test can be used when dependent variable is at the ordinal level of measurement or is not distributed normally.