Chapter 11 - Special Designs

Question 1

single case designs

Answer 1

• participants’ behaviour is first measured during a baseline control time period, then the manipulation is introduced during a treatment period.
  Ex. ABA reversal design, ABAB reversal design, Multiple baseline design

Question 2

ABA (single-reversal) design

Answer 2

• Go from baseline to treatment back to baseline
• Ex. Give food without energy drink for 5 days, give food with energy drink for 5 days, give food without energy drink for 5 days
• Big problem: because you’re only measuring something 1 time with 1 person, it’s hard to tell whether or not the treatment was effective or if something else caused that change
• How to solve this problem: multiple reversals (ex. Abab, ababab)
• Generally suffer from lack of generalizability (because the 1 person you’re running the tests on may not be representative of everyone else) -> must be replicated if you want to infer something larger

Question 3

quasi-experiments

Answer 3

• No randomization
• Uses pre-existing groups (or allows participants to sort themselves into groups)
• Randomization is not possible or unrealistic

Question 4

types of quasi-experimental designs

Answer 4

• One-group post-test only
• One group pretest-posttest
• Nonequivalent control group
• Nonequivalent control group pretest-posttest
• Multiple repeated measures

Question 5

one-group post-test only

Answer 5

• type of quasi-experimental design
• no pre-test, no control group -> no internal validity
• ex. Quit smoking program offered -> students sign up (forming your participant group) -> implement the program (treatment) -> smoking frequency is now 1 pack/week (posttest)

Question 6

one-group pre-test post-test

Answer 6

• type of quasi-experimental design
• no control group, but there is a pre-test which gives us some kind of comparison -> a bit of internal validity
• ex. quit smoking program offered -> students sign up (forming your participant group) -> smoking frequency is measured as 4 packs/week (pretest) -> implement the program (treatment) -> smoking frequency is now 1 pack/week (posttest)

Question 7

nonequivalent control group

Answer 7

• type of quasi-experimental design
• Experimental group is tested alongside a group not receiving treatment
• Problem: you don’t know whether your groups were equivalent because no random assignment is used (you group based on existing natural groups)

Question 8

nonequivalent control group pre-test post-test

Answer 8

• type of quasi-experimental design (and one of the most internally valid)
• Experimental group is tested alongside a group not receiving treatment
• Although random assignment isn’t used, you can give a pretest to see whether your groups were equivalent

Question 9

Multiple repeated measures

Answer 9

• Interrupted time series

- Control series

Question 10

similarities between quasi-experiments and correlational designs

Answer 10

• No randomization
• Outcome variables are measured
• Challenges to causal claims
• Can deal with discrete groups or continuous variables (Quasi-experiments can deal with multiple discrete groups; correlational designs can deal with only two discrete groups)

Question 11

can experiments be both quasi-experimental and correlational?

Answer 11

• Yes!
• Ex. Men’s hair length vs. Women’s hair length
• Measuring variables, not manipulating (correlational)
• Looking at two groups that can’t be randomly assigned because you can’t assign someone to be male or female (quasi-experimental)

Question 12

types of developmental designs

Answer 12

• Cross-sectional
• Longitudinal
• Sequential

Question 13

threats to internal validity

Answer 13

• History
• Maturation
• Testing
• Instrument decay
• Regression towards the mean
• Mortality
• Selection effects
• Cohort effects

Question 14

history

Answer 14

• threat to internal validity

- any event happening between first and second measurements

Question 15

maturation

Answer 15

• threat to internal validity

- people change over time (fatigue effect, get hungrier, more mature, etc.) independent of manipulation

Question 16

testing

Answer 16

• threat to internal validity

- taking a pretest is enough to change a participant’s posttest (eg. Practice effect)

Question 17

instrument decay

Answer 17

• threat to internal validity

- characteristics of a measure, or people’s use of a measure, changes over time (ex. TA’s marking tests)

Question 18

regression towards the mean

Answer 18

• threat to internal validity
• participants, who are selected because of their extreme scores, tend to subsequently score closer to the mean (ex. If you get 1% on a midterm, odds are very likely that you’ll do better than 1% on the second one)

Question 19

Strengths and Weaknesses of ABA reversal design

Answer 19

weak on all – history, maturation, testing, instrument decay, regression towards the mean

Question 20

Strengths and Weaknesses of one group post-test only design

Answer 20

weak on history, maturation, and regression towards the mean

Question 21

Strengths and Weaknesses of one group pre-test post-test design

Answer 21

weak on all – history, maturation, testing, instrument decay, regression towards the mean

Question 22

Strengths and Weaknesses of nonequivalent control group

Answer 22

Good on history and maturation, weak on regression towards the mean

Question 23

Strengths and Weaknesses of Non-equivalent control group pretest-posttest

Answer 23

Good on history, maturation, testing, and instrument decay, weak on regression towards the mean

Question 24

cross-sectional design

Answer 24

• type of developmental design
• taking people of different age groups and testing them all at the same time (ex. Taking 40-year-olds, 60-year-olds, and 80-year-olds and testing their willingness to believe things they read on the internet)
• Problem: cohort effects

Question 25

longitudinal design

Answer 25

• type of developmental design
• studying the same group of people over time (ex. Taking the 40-year-olds and measuring them at 40, then again at 60, then again at 80)
• Problem: mortality effects, expensive

Question 26

sequential design

Answer 26

• type of developmental design
• combining both cross-sectional and longitudinal -> taking different cohorts of people and measuring them longitudinally (ex. Taking 40 year olds and measuring them at 40, 50, and 60; while also taking 60 year olds and measuring them at 60, 70, and 80)
• Problem: still very expensive, but less risky

Question 27

multiple baseline design

Answer 27

• introducing a manipulation under multiple circumstances to see if behaviour changes
• Variations: across participants, across behaviours, across situations

Question 28

across participants

Answer 28

measuring several participants’ behaviour over time, introducing the manipulation at a different point in time for each participant

Question 29

across behaviours

Answer 29

several different behaviours of a participant are measured over time; at different times, the same manipulation is applied to each of the behaviours

Question 30

across situations

Answer 30

the same behaviour is measured in different settings (such as at home and at school)

Question 31

program evaluation

Answer 31

• research on programs implemented to achieve a positive effect on a group of people (ie. Schools, work settings, communities)
• Use 5 questions to evaluate: needs assessment, program theory assessment, process evaluation, outcome evaluation, efficiency assessment

Question 32

mortality

Answer 32

• threat to internal validity

- when participants leave the study

Question 33

selection effects

Answer 33

• threat to internal validity

- random assignment isn’t used to divide groups; group differences create alternative explanations for results

Question 34

cohort effects

Answer 34

• threat to internal validity
• type of selection effect
• groups are divided by age, and the experiences of each different cohort offer alternative explanations for results

Question 35

interrupted time series design

Answer 35

examine variable of interest over an extended period of time, both before and after manipulation

Question 36

control series design

Answer 36

similar to the interrupted time series design, but uses a control group