Types of Variables and Data

Question 1

_____ is what a researcher believes has an effect on the dependent variable and on which research participants differ, either because they’re exposed to different levels of it during the study or because they begin the study with different levels.

Answer 1

The independent variable, which always has at least two levels (e.g. treatment vs. no treatment)

Question 2

A _____ affects the direction and/or strength of the relationship between independent and dependent variables.

Answer 2

moderator variable

e.g., CBT might be more effective in treating teens with anxiety if the parents have authoritative styles.

Question 3

A _____ explains the relationship between independent and dependent variables.

Answer 3

mediator variable

e.g., CBT (IV) leads to more reaslitic thinking (mediator) which leads to reduced anxiety (DV)

Question 4

______ are not an intentional part of a research study but affect the relationship between the study’s independent and dependent variables and make it difficult to determine if an apparent effect of an independent variable on a dependent variable is actually due to the independent variable.

Answer 4

Extraneous variables

Question 5

Variables measured on a _____ divide people into unordered categories.

Answer 5

nominal scale

Question 6

Variables measured on an _____ divide people into categories that are ordered in terms of magnitude.

Answer 6

ordinal scale

When a variable is measured on an ordinal scale, you can conclude that one person has more or less of the characteristic being measured but you cannot determine how much more or less

Question 7

Variables measured on an _____ assign people to ordered categories, with the difference between adjacent categories being equal. Scores on standardized tests often represent this.

Answer 7

interval scale

Note, however, that interval scales do not have an absolute zero point: Even if it were possible for an examinee to obtain a score of 0 on an IQ test, this would not mean the examinee has no intelligence.

Question 8

Variables measured on a _____ assign people to ordered categories, with the difference between adjacent categories being equal and the scale having an absolute zero point.

Answer 8

ratio scale

Question 9

A normal distribution is symmetrical and bell-shaped and has certain characteristics, including….

Answer 9

1. All three measures of central tendency are equal
2. • |- 1 SD from mean = 68%
     +|- 2 SD from mean = 95%
     +|- 3 SD from mean = 99%

Question 10

In a _____, the mean has the lowest value, the median is the middle value, and the mode has the highest value.

Answer 10

negatively skewed distribution

Question 11

In a ____, the mean has the highest value, the median is the middle value, and the mode has the lowest value.

Answer 11

positively skewed distribution

Question 12

A _____ has a sharper peak and flatter tails than a normal distribution (i.e., most scores are “piled up” in the middle of the distribution).

Answer 12

leptokurtic distribution

Question 13

A _____ is flatter in the middle and has thicker tails than a normal distribution (i.e., scores are more evenly distributed throughout the distribution).

Answer 13

platykurtic distribution