SCEDS

Question 1

What are the four types of single case experimental designs?

Answer 1

1) withdrawal-reversal design
2) multiple baseline design
3) alternating-treatments design
4) changing-criterion design

Question 2

Explain the withdrawal reversal design

Answer 2

When a treatment is introduced and then removed, and a change in the DV is assessed. This should only be used when the intervention can be meaningfully and ethically withdrawn (e.g., use of a pager to help with memory rather then teaching a new skill).
Needs to have 5 data points and 4 phases (e.g., AB, AB, AB, AB, each with 5 data points) to meet standards of evidence

Question 3

Explain the multiple baseline design

Answer 3

They consist of several chronologically anchored A-B sequences, with each A-B sequence acting as a baseline or their of the design.
Target behaviour is simultaneously and continually measured over time across each tier, and only one intervention is measured. Several DVs are measured concurrently.
Needs 6 A-B phases, each with 5 data points.
Ad = can be used even if there are irreversible effects on the target behaviour.

Question 4

Explain the alternating treatments design

Answer 4

When two or more interventions are presented to the same client in rapid alternation (either on same day or diff days). Is used for:
- Comparing two or more interventions with withdrawable effects and
- comparing an intervention with no intervention

Each intervention needs to be administered the same number of times and sequentially presented in counterbalanced or randomised sequence to avoid order effects

Needs at least 5 replications of the alternating sequence to meet standards of evidence

Question 5

Explain the changing criterion design

Answer 5

Modelled on operant conditioning schedules for gradually shaping behaviour (e.g., positive reinforcement through obtaining a soft drink).
Each subphase needs 5 data points and the experimental effect is replicated on at least three performance criteria (stepwise changes in criterion)

Question 6

What designs would you consider when the intervention cannot be meaningfully withdrawn?

Answer 6

Multiple baseline design with 3 A-B tiers or changing criterion of 4 steps

Question 7

What designs would you consider when the intervention CAN be meaningfully withdrawn?

Answer 7

A-B-A-B withdrawal reversal design with 4 phases
OR
Alternating treatments design (with 5 sets of repetition)