Deck 17: Testing for Differences Between Two Samples

Question 1

1) Children in two English classes have been matched. One class has undergone an experimental teaching method designed to improve spelling. Both groups undergo a spelling test at the end of the experimental programme. The data meet parametric requirements so the most suitable difference test is:

A) An unrelated t test
B) A related t test
C) A Mann-Whitney test
D) A Wilcoxon matched pairs test

Answer 1

B

Question 2

2) A researcher wishes to test the difference between two samples of data where each sample has been produced by a different group of participants. The data are found to be highly skewed and this skew cannot be removed by transformation. The researcher could:

A) Proceed with a related t test
B) Proceed with an unrelated t test
C) Proceed with a Mann-Whitney test
D) Proceed with a Wilcoxon matched pairs test

Answer 2

C

Question 3

3) A set of data produce a two-tailed unrelated t of 2.043 in an experiment where there were 14 participants in one group and 17 in the other. The difference tested is:

A) Significant with p < .05
B) Significant with p < .01
C) Not significant at the 5% level
D) Difficult to analyse since the df do not appear in the table

Answer 3

C

Question 4

For the following set of data produced in an independent samples experiment
experimental group: 23, 34, 45, 34, 37, 38, 25, 42
control group: 11, 35, 19, 42, 27, 18, 27, 15, 21, 19
-4) the t value is:

A) 2.698
B) 2.819
C) 2.990
D) 2.749

Question 5

For the following set of data produced in an independent samples experiment
experimental group: 23, 34, 45, 34, 37, 38, 25, 42
control group: 11, 35, 19, 42, 27, 18, 27, 15, 21, 19
-5) The degrees of freedom involved with the t value just found are:

A) 18
B) 17
C) 16
D) 15

Question 6

For the following set of data produced in an independent samples experiment
experimental group: 23, 34, 45, 34, 37, 38, 25, 42
control group: 11, 35, 19, 42, 27, 18, 27, 15, 21, 19
-6) The difference tested after "The degrees of freedom involved with the t value just found ", using a two-tailed analysis:

A) Is significant with p < .001
B) Is significant with p < .01
C) Is significant with p < .05
D) Is not significant at the 5% level

Question 7

7) Lack of homogeneity of variance is most problematic when:

A) Sample sizes are equal and a repeated measures design is used
B) Sample sizes are unequal and a repeated measures design is used
C) Sample sizes are equal and an independent samples design is used
D) Sample sizes are very unequal and an independent samples design is used

Question 8

8) The power of a significance test is:

A) The probability that it will not produce a type I error
B) The probability that it will produce a type I error
C) The probability that it will not produce a type II error
D) The probability that it will produce a type I error

Question 9

9) Which of the following will not increase power:

A) Increasing sample size
B) Increasing the effect size
C) Decreasing the population variance
D) Increasing the standard deviation of the population

Question 10

10) Non-normal data can be transformed to normal by:

A) Squaring each score
B) Taking the square root of each score
C) Taking a log of each score
D) All of the above