# Chapter 1: Why you need science

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 best describes a confounding variable?

1. A variable that is manipulated by the experimenter.
2. A variable that has been measured using an unreliable scale.
3. A variable that affects the outcome being measured as well as, or instead of, the independent variable.
4. A variable that is made up only of categories.

The correct answer is C. A variable that affects the outcome being measured as well as, or instead of, the independent variable. This is correct because a confounding variable is an unforeseen and unaccounted-for variable that jeopardizes the reliability and validity of an experiment’s outcome.

2.   A variable that measures the effect that manipulating another variable has is known as:

1. A dependent variable
2. A confounding variable
3. A predictor variable
4. An independent variable

The correct answer is A. This is because a dependent variable (or outcome variable) is a variable that is thought to be affected by changes in an independent variable.

3. A predictor variable is another name for:

1. A dependent variable
2. An independent variable
3. A confounding variable
4. A discrete variable

The correct answer is B. An independent variable. An independent variable (or predictor variable) is a variable that is thought to be the cause of some effect. This term is usually used in experimental research to denote a variable that the experimenter has manipulated.

4. Which of the following statements is true about inferential statistics?

1. They describe relevant information about the population of interest
2. They provide us with a summary of the sample and population
3. They allow for extrapolating results from the data to the population
4. They use a different set of data to make generalisations of the sample data to the whole population

The correct answer is C. While descriptive statistics summarise relevant aspects of the sample data, inferential statistics are aimed at generalising these findings to the whole population.

5. Which of the following is designed to compensate for practice effects?

1. repeated measured design
2. Counterbalancing
3. Giving participants a break between tasks
4. A control condition

The correct answer is B. Counterbalancing. This is because although practice effects are impossible to eliminate completely, we can ensure that they produce no systematic variation between our conditions by counterbalancing the order in which a person participates in a condition.