Module 5: Defining, Measuring, and Manipulating Variables

Question 1

Operational definition

Answer 1

An operational definition specifies the activities of the researcher in measuring and/or manipulating a variable.

Question 2

4 properties of measurement

Answer 2

• Identity
• Magnitude (or ordinality)
• Equal unit size
• Absolute zero

Question 3

Identity

Answer 3

A property of measurement in which objects that are different receive different scores. Such as the participants’ religion (1= catholic, 2= Islam, etc.).

Question 4

Magnitude (or ordinality)

Answer 4

A property of measurement in which the ordering of numbers reflects the ordering of the variable (hot peppers divided on a scale from 1 to 10, 1= green pepper, 10= the hottest). You can’t switch them around without messing up the meaning.

Question 5

Equal unit size

Answer 5

A property of measurement in which a difference of 1 is the same amount throughout the entire scale. (Centimeters, liters, etc.)

Question 6

Absolute zero

Answer 6

A property of measurement in which assigning a score of zero indicates an absence of the variable being measured (the time you studied, because it can also be 0). Watch out! A property of zero is not always absolute zero, for example degrees in Fahrenheit. 0 doesn’t mean the lack of temperature, it just means in it’s very cold.

Question 7

4 scales (levels) of measurement

Answer 7

Each of these scales has one or more of the properties (levels of measurement) described in the previous section.
1 Nominal
2 Ordinal
3 Interval
4 Ratio

Question 8

Nominal

Answer 8

A scale in which objects or individuals are assigned to categories that have no numerical properties. Variables measured on a nominal scale are often referred to as categorical variables because the data are divided into categories. However, the categories carry no numerical weight. Some examples of categorical variables, or data measured on a nominal scale, are ethnicity, gender, and political affiliation.

Question 9

Ordinal

Answer 9

A scale in which objects or individuals are categorized and the categories form a rank order along a continuum. Ordinal data are often referred to as ranked data because they are ordered from highest to lowest or from biggest to smallest. For example, reporting how students did on an examination based simply on their rank (highest score, second highest, and so on) involves an ordinal scale.

Question 10

Interval

Answer 10

A scale in which the units of measurement (intervals) between the numbers on the scale are all equal in size, i.e. temperature, and psychological tests.

Question 11

Ratio

Answer 11

A scale in which in addition to order and equal units of measurement there is an absolute zero that indicates an absence of the variable being measured. Examples of ratio scales of measurement include weight, time, and height. Each of these scales has (1) identity (individuals with different weights receive different scores), (2) magnitude (those who weigh less receive lower scores than those who weigh more), and (3) equal unit size (1 pound is the same unit of weight anywhere along the scale). Ratio scales also have an absolute zero, meaning that a score of zero reflects an absence of the variable.

Question 12

Discrete variables

Answer 12

Discrete variables consist of whole number units or categories. They are detached and distinct from one another and decimals do not make sense. They are mostly nominal and ordinal. For example, gender, political party and ethnicity.

Question 13

Continuous variables

Answer 13

Continuous variables usually fall along a continuum and allow for fractional amounts. Continuous simply means that it “continues” between the whole number units, such as age (22.7 years), and height (1.62 meter). Mostly interval and ratio.

Question 14

4 types of measures (research methods)

Answer 14

When researchers collect data, the types of measures (i.e. the used research method) can be classified into four basic categories:

• Self-report measures
• Tests
• Behavioral measures
• Physical measures

Question 15

Self-report measures with 3 sub-categories

Answer 15

Typically, self-report measures are questionnaires or interviews to measure how people report that they act, think or feel.

• Behavioral
• Cognitive
• Affective

Question 16

Behavioral self-report measures

Answer 16

Ask people to report how often they do something (eat certain food, go to the gym, have sex, etc.).
• Con: you rely on the individual to report on their own behaviors. It is unknown how accurate the reports are, because of the reporting or their memory.
• Pro: Useful when you can’t observe an event directly, either because of ethics or it’s just not possible.

Question 17

Cognitive self-report measures

Answer 17

Asks what individuals think about something.

• Con: You rely on an individual to make an accurate and truthful report.

Question 18

Affective self-report measures

Answer 18

Asks individuals to report how they feel about something, concerning emotional reactions such as happiness, anxiety or stress. Are also measurement tests (next section).

Question 19

Tests with 2 sub-categories

Answer 19

Tests are measurement instruments used to assess individual differences in various content areas. Psychologists frequently use two types of tests:

• Personality tests
• Ability tests.

Question 20

Personality tests

Answer 20

Personality tests are designed to measure aspects of an individual’s personality and feelings about certain thing, such as the Beck Depression Inventory. (This can be the same as affective self-report measures.)

Question 21

Ability test with 2 sub-categories

Answer 21

Ability tests are not self-report measures and can be divided into two categories.

• Aptitude tests measure an individual’s potential to do something, such as intelligence tests.
• Achievement tests measure an individual’s competence in an area, such as school exams.
• Pro: Most tests have been tested themselves and can be considered objective, unbiased means of collecting data.
• Con: Any measuring instrument has the potential for problems, which may range from the state of the participant on a given day to scoring and interpretation.

Question 22

Behavioral measures (or observational measures)

Answer 22

Behavioral measures are carefully observed by researchers and recorded and are also referred to as observational measures, because they involve observing what a participant does. The observation can be direct (while the participant is engaging in the behavior) or indirect (via audio- or videotape).

Con: They rely on humans observing events, how accurate did they perceive it?
Second, the observer must code the events in numerical format, where there is room for error.
Third, a researcher at a stop sign might influence the behavior of the drivers. How realistic are the results then?

Question 23

Reactivity

Answer 23

A possible reaction by participants in which they act unnaturally because they know they are being observed

Question 24

Physical measures

Answer 24

Physical measures, or measures of bodily activity, are not directly observable. Physical measures are usually taken by means of equipment. Weight is measured with a scale, blood pressure with a sphygmomanometer, and temperature with a thermometer.

• Pro: Physical measures are more objective than behavioral measures.
• Con: Are not directly observable. Equipment is still set-up by humans and can contain errors.

Question 25

Variables/attributes

Answer 25

An event or behavior that has at least two values (e.g. pass and fail, male and female, etc.)

Question 26

Constant

Answer 26

If there is only one value

Question 27

How can a variable be seen?

Answer 27

• Directly observable (hair color)
• Indirectly observable (answer to a question about hair color)
• Unobservable constructs (text comprehension/intelligence)

Question 28

Which factors do you need to specify with operationalization of constructs?

Answer 28

• Indicators: observation that reflects the construct
• Dimensions: groupings of indicators

E.g.: Example corporate image:

• Dimensions: reliability, attractiveness, expertise
• Indicators of reliability: honesty, sincerity, trustworthiness

Question 29

Non-reactivity

Answer 29

With as little disturbance of the natural setting as possible.