Chapter 11: Confounding and Obscuring Variables

Question 1

One - Group Pretest/Posttest Design

Answer 1

• Lack of comparison groups
• A researcher recruits one group of participants, measures them on a pretest, exposes them to a treatment or change and then measures them on postest

Question 2

Maturation Threats

Answer 2

Change in behavior that emerges spontaneously over time

Question 3

History Threat

Answer 3

A “historical” or external factor that systematically affects most members or the treatment group at the same time as the treatment itself, making it unclear weather the change is caused by the treatment received

Question 4

Regression Threat

Answer 4

Occurs only when a group is measure twice and only when the group has an extreme score at pretest

Question 5

Attrition Threat

Answer 5

Attrition is only problematic when it is systematic (when certain groups of participants are dropping out due to characteristics related to the variables being studied)

Question 6

Testing Threat

Answer 6

• When participants responses on a posttest measure are influenced by their exposure to the pretest measure
• That exposure can affect the responses
• Specific kinds of order effect
• Refers to a change in the participants as a result of taking a test (dependent measure) more than once

Question 7

Instrumentation Threat

Answer 7

• Changes in the instrument/observers which may produce changes in outcomes
• If the equipment starts to fail, it will lead to an inaccurate response
• Make sure the pre test is equivalent

Question 8

Observer Bias

Answer 8

• Observer is looking for a certain result
• Can influence the observation which lead changes in the scores

Question 9

Double Blind Study

Answer 9

In which neither the participants nor the researchers who evaluate them know who is in the treatment group and who is in the comparison group

Question 10

Masked Design

Answer 10

Participants know which groups they are in, but the observers do not

Question 11

Placebo Effect

Answer 11

• Designing studies to rule out the placebo effect (double blind placebo control study)
• People can experience the benefits just for being in the study
• Patient think they are getting something but they actually do not

Question 12

Manipulation Effect

Answer 12

Is a separate dependent variable that experimenters include in a study, specifically to make sure the manipulation worked

Question 13

Measurement Error

Answer 13

• Any factor that can inflate or deflate a person’s true score on the DV
• Solutions for reducing measurement error:
  — Use reliable, precise measurements
  — Measure more instances

Question 14

Individual Differences

Answer 14

• Individual differences spread out scores within each group
• Another source of within group variability
• Solutions for reducing the effects of individual differences:
  — Change the design to a within - groups or matched groups design
  — Add more participants

Question 15

Situation Noise

Answer 15

• Situation noise is any kind of external distraction that could cause variability within - groups that obscure between groups differences
• Third factor that could cause variability within groups and obscure true group differences
• It can be minimized by controlling the surroundings of an experiment
• Another Name for These Solutions: Power