Question

1 A researcher wants to find out which type of classroom instruction significantly improves students’ test performance. He designed four types of instruction for four samples of students. Later all four samples were given the same test and their average performance was compared. What statistical test should be used by the researcher to analyze the results of this study?

• A. Pearson correlation
• B. t-test for independent groups
• C. one-factor Anova for between groups
• D. Chi² for Independence

2 A researcher wanted to know if there is a relationship between gender and academic performance in high school students. The researcher randomly selected a sample of n = 100 students and recorded how many students received each final letter grade (i.e., A, B, C, D and F grades)   and number of females and males in each letter grade category. What statistical test should the researcher use to test if there is a relationship between gender and the final letter grades received by high school students?

• A. Pearson’s correlation
• B. t- test for repeated-measures
• C. 1- factor Anova
• D. Chi² for Independence

3 By selecting a smaller statistical significance level (e.g., p < .01 instead of p < .05) a researcher is __________.

• A. making it easier to reject H₀
• B. making it harder to reject H₀
• C. reducing the risk of a Type I error
• D. increasing the risk of a Type I error
• E. B & C
• F. A & D
• G. None of the above.

4 In hypothesis testing, committing Type II error means that a researcher has _____________.

• A. correctly concluded that there is no significant mean difference or correlation.
• B. correctly concluded that there is a significant mean difference or correlation.
• C. falsely concluded that the mean difference or correlation in his/her study is significant.
• D. falsely concluded that the mean difference or correlation in his/her study is not significant.

5 An average variability of sample means in a distribution of sample means is called _______.

• A. standard deviation
• B. standard error (or estimated standard error)
• C. estimated variance
• D. None of the above.

6

A researcher examined the effect of distraction (i.e., no distraction vs. high level of distraction) and reward size (no reward vs. $10 reward) on task performance. She used a two-factor ANOVA to analyze her data. If the results of ANOVA showed a significant main effect of distraction on task performance that means_________.

• A. the mean performance of participants tested under different levels of distraction is significantly different.
• B. the mean performance of participants tested under different levels of reward is significantly different.
• C. the effect of reward on performance significantly differs under no distraction vs. high distraction conditions (i.e., the reward affects performance significantly different depending on the level of distraction).
• D. None of the above.

Answer 1

(1)

Correct option:

C. one-factor Anova for between groups

Explanation:
Here the researcher is determining whether there are any statistically significant differences between the means of 4 independent groups.

(2)

Correct option:

A. Pearson’s correlation

Explanation:

Here the researcher is finding the correlation between grades obtained by females and males

(3)

Correct option:

B & C

Explanation:

By selecting a smaller statistical significance level, we are less likely to reject H0. We lower the risk of rejecting a true H0.

(4)

Correct option:

D. falsely concluded that the mean difference or correlation in his/her study is not significant.

Explanation:

Type II is failure to reject a false null hypothesis

(5)

Correct option:

B. standard error (or estimated standard error)
Explanation:

The Standard Error is the Standard Deviation of the Sampling Distribution of the Sample Statistic.

(6)

Correct option:

A. the mean performance of participants tested under different levels of distraction is significantly different.