# Multiple choice questions

Quizzes are available to test your understanding of the key concepts covered in each chapter. Click on the quiz below to get started.

1.    Which of the following transformations is most useful for correcting skewed data?

1. Tangent transformation
2. Arcsine transformation
3. Cosine transformation
4. Log transformation

The correct answer is d) Log transformation. This is because taking the logarithm of a set of numbers squashes the right tail of the distribution. As such it’s a good way to reduce positive skew.

2.    The assumption of homogeneity of variance is met when:

1. The variances in different groups are significantly different.
2. The variances in different groups are approximately equal.
3. The variance across groups is proportional to the means of those groups.
4. The variance is the same as the interquartile range.

The correct answer is b) The variances in different groups are approximately equal. This is because to make sure our estimates of the parameters that define our model and significance tests are accurate, we have to assume homoscedasticity (also known as homogeneity of variance).

3.    Imagine you conduct a t-test using IBM SPSS and the output reveals that Levene’s test for equality of variance is significant. What should you do? (Hint: Levene’s test tests the assumption that variances in
different groups are approximately equal.)

1. Interpret the figures in the row labelled ‘equal variances assumed’.
2. Conduct a Kruskal–Wallis test instead.
3. Interpret the figures in the row labelled ‘equal variances not assumed’.
4. Collect more data.

The correct answer is c) Interpret the figures in the row labelled ‘equal variances not assumed’.