Lecture 2

Question 1

Explain

Answer 1

Finding out what caused behavior

Question 2

Control

Answer 2

Changing causes

Question 3

Causation

Answer 3

Experiment - one factor directly affects another factor

Question 4

To Show Causation We Must Demonstrate That

Answer 4

1. Changing the first thing produces a change in the second
2. There is no other possible cause for the change in the second thing

Important – rule out alternative explanations or hypotheses

Question 5

Components Of An Experiment

Answer 5

Population And Sample
Dependent Variable (DV)
Operational Definition
Reliability And Validity 
Bias

Question 6

Population

Answer 6

Members of a specific group

Question 7

Sample

Answer 7

Relatively small subset of a population that is selected to represent the population

Question 8

Representative Sample

Answer 8

Characteristics and behavior of the sample reflect those of the population (ensures generalizability)

Question 9

Representative Sample Achieved By

Answer 9

Random sampling

- Selected members in an unbiased manner - all members have an equal chance of selection

Question 10

Descriptive Statistics

Answer 10

Summarize the data collected from the sample

Question 11

Inferential Statistics

Answer 11

Generalize from the sample to the population

Question 12

Dependent Variable (DV)

Answer 12

The measure taken

What you record (depends on what the participant does)

Question 13

Operational Definition

Answer 13

Specification of how property of interest will be measured

Question 14

Validity

Answer 14

A dependent variable is valid if it measures what it is supposed to

Threat to validity arises from any unintended component that is reflected in a score

Therefore a poor operational definition can result in an invalid dependent variable

Question 15

Reliability

Answer 15

A dependent variable is reliable if, under the same conditions, it gives the same measure, and contains a minimum of measurement error

Unreliable data reflect error and provide a biased perspective

If a measure lacks reliability it also lacks validity

Question 16

Bias

Answer 16

A biased dependent variable is consistently inaccurate in one direction (i.e. always high, or always low)

Question 17

A Good Dependent Variable Is

Answer 17

Valid
Reliable
Unbiased

Question 18

Ceiling Effect

Answer 18

When a task is so easy that all scores are very high

Question 19

Floor Effect

Answer 19

When a task is so difficult that all scores are very low

Question 20

Floor And Ceiling Effects

Answer 20

Both mask differences between groups

Question 21

Data Types And Scales Of Measurement

Answer 21

Every dependent variable has a data type

The data type determines what sorts of analyses you can perform on your data, and the conclusions you can draw

Data types are associated with different scales of measurement

The type of scale of measurement dictates the type of conclusion that you can draw

Question 22

Nominal Scale

Answer 22

• Categorizes without ordering
• Numbers that substitute
• E.g. gender 1 – Female, 2 – Male

Question 23

Ordinary Scale

Answer 23

• Categorizes and orders the categories
• Bigger means more
• Distance between points on the scale is not considered equal
• E.g. rugby team standings

Question 24

Interval Scale

Answer 24

• Categorizes, orders, and establishes an equal unit of measurement in the scale
• Knowing how much more
• Distance between points on the scale considered equal
• E.g. Celsius temperature

Question 25

Ratio Scale

Answer 25

• Categorizes, orders, establishes an equal unit in the scale, and contains a true zero point
• Allows ration statements e.g. twice as big
• E.g. number of items recalled in a memory task

Question 26

Examples

Answer 26

•	John is twice as lazy as Peter
-	Ratio
•	John is lazy but Peter is not 
-	Nominal
•	John is lazier than Peter 
-	Ordinal