## Multiple choice questions

A researcher was interested in stress levels of lecturers during lectures. She took the same group of 8 lecturers and measured their anxiety (out of 15) during a normal lecture and again in a lecture in which she had paid students to be disruptive and misbehave. What test is best used to compare the mean level of anxiety in the two lectures?

1. Independent samples t-test
2. Paired-samples t-test
3. One-way independent ANOVA
4. Mann–Whitney test

What does the error bar on an error bar chart represent?

1. The confidence interval around the mean.
2. The standard error of the mean.
3. The standard deviation of the mean.
4. It can represent any of these.

#### Answer: It can represent any of these

The t-test tests for:

1. Differences between means
2. Whether a correlation is significant
3. Whether a regression coefficient is equal to zero
4. All of these

Differences between group means can be characterized as a regression (linear) model if:

1. The experimental groups are represented by a binary variable (i.e. coded 0 and 1).
2. The outcome variable is categorical.
3. The groups have equal sample sizes.
4. Differences between group means cannot be characterized as a linear model, they must be analysed with an independent t-test.

#### Answer: The experimental groups are represented by a binary variable (i.e. coded 0 and 1)

A researcher measured people’s physiological reactions to horror films. He split the data into two groups: males and females. The resulting data were normally distributed and men and women had equal variances. What test should be used to analyse the data?