Chapter 10: Introduction to Simple Experiments

Question 1

Experiment

Answer 1

• Specifically means that the researchers manipulated at least one variable and measured another
• It can take place in a laboratory and just about anywhere else - anywhere a researcher can manipulate one variable and measure another

Question 2

Manipulated Variable

Answer 2

A variable that is controlled, such as when the researchers assign participants to a particular level (value) of the variable
- Independent variable

Question 3

Measured Variable

Answer 3

• Take the from of records of behavior or attitudes, such as self - reports, behavioral observations, or psychological measures
• The researchers simply record what happens
• Dependent variable

Question 4

Conditions

Answer 4

Levels of an indepedent variable (and it should not be confused with it’s levels)

Question 5

Control Variable

Answer 5

• Any variable that an experimenter holds constant
• Want to make sure all participants are identical except the variable that is being manipulated
• Also called the nuisance variable

Question 6

Comparison Group

Answer 6

(comparison condition)
- If the independent varibales did not vary, a study should not establish covariance

Question 7

Treatment Group(s)

Answer 7

(one or more treatment conditions)
- Give variables on each side such as doeses of medication

Question 8

Control Group

Answer 8

(no treatment condition)
- It is a level of an independnt variable that is intended to represent “no treatment” or a neutral condition

Question 9

Placebo Group

Answer 9

(placebo control group; appears to the participants to be an active treatment, but does not actually contain the active treatment)
- When the control group is exposed to a treatment such as sugar

Question 10

Experiments Establish Temporal Precedence

Answer 10

• Where the cause variable precedes the effect variable
• The ability to establish temporal precedence, by controlling which variables come first, is a strong advantage of experimental designs
• The ability to establish temporal precedence is a feature that makes experiments superior to correlational designs

Question 11

Confound

Answer 11

• Or potential threats to internal validity
• Can mean confuse
• When a study has a confound, you are confused about what is causing the change in the dependent variable

Question 12

Design Confound

Answer 12

• Is an experimenters mistake in designing the independent variable
• Is a classic threat to internal validity
• When a experiment has a design confound, it has poor internal validity and cannot support a causal claim

Question 13

Systematic Varibality

Answer 13

• Don’t want another variable making a change
• It’s a problem
• It is important to reduce systematic variability through proper experimental design and control

Question 14

Unsystematic Variability

Answer 14

• Less of a problem
• Change that is not consistent
• It is somewhat random

Question 15

Selection Effect

Answer 15

• When participants in one level is systematic different than the other participants conditions
• When the experimenters let participants choosle (select) which group they want to be in
• May result if the experimenters assign one type of person to one condition, and another type of person to another condition

Question 16

Random Assignment

Answer 16

• Avoids selection effect
• Random assignment is where every participants have an equal chance of any conditions
• Well-designed experiments often use random assignment to avoid selection effects
• Is a way of systematizing the types of participants who end up in each level of the independent variable

Question 17

Independent Group Design

Answer 17

(aka between sibjects design or between groups design)
- When participanst are exposed to just one level of condition

Question 18

Matched Groups

Answer 18

• Avoiding selection effects
• Has the advantage of randomness
• Requires more time and often more resources than random assignment

Question 19

Within Group Design

Answer 19

(aka within - subjects design)
- Each particpansts are exposed to all levels of conditions

Question 20

Posttest - Only Design

Answer 20

• Participants are randomly assigned to each level and are tested on the dependent variable once
• Also known as as an equivalent groups

Question 21

Within - Groups Designs

Answer 21

Participants are exposed to all conditions (levels)

Question 22

Repeated - Measures Design

Answer 22

Is a type of within - groups design in which participants are measured on a dependent variable more than once, after exposure to each level of the independent variable

Question 23

Concurrent - Measures Design

Answer 23

Which is when all conditions are exposed roughly at the same time and a single attitudinal or behavioral preference is the dependent variable

Question 24

Advanatages of Within - Groups Designs

Answer 24

1. Participants in your groups are equivalent because they are the same participants and sevres as their own controls
2. These designs give researchers more power to notice differences between conditions
3. Within - groups designs require fewer participants than other designs

Question 25

Power

Answer 25

Refers to the probability that a study will show a statistically significant result when a independent variable truly has an effect in the population

Question 26

Order Effects

Answer 26

When being exposed to one condition affects how participants respond to other conditions (exposed to one condition exposed how other conditions react)

Question 27

Practice Effects

Answer 27

• Which can happen when participants do better on a test due practice they have done
• Also known as fatigue effects

Question 28

Carryover Effects

Answer 28

When there is a lasting effect that is being carried over one condition to another

Question 29

Counterbalancing

Answer 29

• They present the levels of the independent variable to participants in different sequence
• In counterbalancing, any order effects should cancel each other out when all the data are collected

Question 30

Full Counterbalancing

Answer 30

• When you are presenting all possible condition order (Which can be really easy)
• Complicated when there is more than 4 conditions
• Less complicated when there is 3 or less conditions

Example: A repeated - measures design with two conditions is easy to counterbalance because there are only two orders (A → B and B → A)

Question 31

Parietal Counterbalancing

Answer 31

• Which only some of the possible conditions are represented
• One way to do it is to present the conditions in a randomized order for every subject

Example: Latin square
- A technique for partial counterbalancing
- A formal system to ensure that every condition appears in each position at least once

Question 32

Disdavantage of Within - Groups Designs

Answer 32

1. Potential for order effects (Solution: counterbalancing)
2. Might not be practical or possible to counterbalance the order
3. Experiencing all levels of the independent variable (IV) changes the way participants act (demand characteristics) (Solution: Asking the participants the purpose of the study)

Question 33

Manipulation Check

Answer 33

• Is an extra dependent variable that researchers can insert into an experiment to convince them that their experimental manipulation worked
• Can help researchers determine whether the operationalization worked as intended

Question 34

Pilot Study

Answer 34

• Simple study
• A test before you actually conduct the study with a small sample
• Used to confirm the effectiveness of their manipulation before using them in a target study

Question 35

Cohen’s Guidelines for Effect Size Strength

Answer 35

d = 0.20
Described as small or weak
Comparable to an r of .10

d = 0.50
Described as medium or moderate
Comparable to an r of .30

d = 0.80
Described as Large or strong
Comparable to an r of .50