# Chapter 3: Summarizing data

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

1. The scores under the curve of a density function represents:

- The relative changes from one score to the next
- The changes to observe a particular score

The correct answer is B. Instead of representing relative frequencies, the probability density function gives the probability

2. A frequency distribution in which there are too many scores at the extremes of the distribution is said to be:

- Positively skewed
- Leptokurtic
- Platykurtic
- Negatively skewed

The correct answer is C. This is because a platykurtic distribution describes a distribution with negative kurtosis and it is relatively thin in the tails (has light tails) and tends to be flatter than normal.

3. A frequency distribution in which there are too few scores at the extremes of the distribution is said to be:

- Leptokurtic
- Positively skewed
- Negatively skewed
- Platykurtic

The correct answer is A. This is because a leptokurtic distribution describes a distribution with positive kurtosis, it has many scores in the tails (a so-called heavy-tailed distribution) and is pointy.

4. Variation due to variables that have not been measured is known as:

- Homogenous variance
- Systematic variation
- Residual variance
- Unsystematic variation

The correct answer is D. This is because unsystematic variation results from random factors that exist between the experimental conditions (such as natural differences in ability, the time of day, etc.)