BCBA Experimental Design practice questions

Question 1

An agency report describes 12 adults in four group homes. For each adult, staff recorded self-injury for two weeks, then added a sensory routine and recorded for two more weeks (an AB design: baseline, then intervention). All routines began in the same week. Self-injury fell for 11 of the 12 adults, for example from 9 to 11 per day down to 3 to 5. The agency concludes the routine is proven and will work in its other homes. As a consulting BCBA, what is the main problem with this conclusion?

Accepted Answer

No case shows experimental control, so there is no demonstrated effect whose generality can be claimed

Answer

External validity is limited, because all participants lived in group homes run by one agency

Answer

The 12 cases are direct replications, which establish internal validity but say nothing about generality

Answer

Generality is established across clients and homes, but social validity must be measured before adoption

Question 2

Omar's parents contact a BCBA after three nights of bedtime crying far above anything they consider typical for him. The BCBA uses those three nights as baseline and starts treatment the next night. Within a week, crying returns to about Omar's usual level. No changes in routine, caregivers, or health were reported. Which threat most limits confidence that the treatment caused the decrease?

Accepted Answer

Statistical regression

Answer

History

Answer

Testing

Answer

Maturation

Question 3

Rosa, a BCBA, is teaching Ethan, 34, who lives in a group home, to use a separate picture checklist for each of three routines: morning hygiene, laundry, and making lunch. Each routine has a stable baseline of about 30% of steps completed independently. Once learned, the skills are unlikely to reverse, and the team will not remove a support Ethan relies on. Which arrangement would still let Rosa verify her baseline predictions and replicate the effect?

Accepted Answer

Start the checklist in one routine at a time while the other routines stay in baseline

Answer

Extend baseline in all three routines, then start the checklist in all three on the same day

Answer

Start the checklist in one routine, then briefly withdraw it there after mastery

Answer

Start the checklist for Ethan and compare his data with an untreated housemate's

Question 4

Jamal, a BCBA, reviews a randomized group study of a feeding intervention with 24 children, 12 per group. Both groups began near 40% bite acceptance, and at the end both group means were still about 40%, so the authors concluded the intervention had no effect. An appendix graphs each child across 20 sessions: 6 treated children rose steadily to about 70%, the other 6 fell to about 10%, and control children stayed near 40%. Which conclusion is best supported?

Accepted Answer

The mean hides two opposite patterns of response, so each child's data need analysis

Answer

The intervention had no effect on acceptance, because the two group means did not differ

Answer

A larger sample was needed to detect the intervention's small but real average effect

Answer

Random assignment likely failed, so the groups were not equivalent before treatment began

Question 5

Imani, a BCBA, reviews a supervisee's ABAB evaluation of a self-management procedure for Caleb, age 16, who curses during chores at his group home. Cursing per shift: A1 10 to 12, B1 3 to 4, A2 9 to 11, B2 2 to 4. The supervisee ran every session and recorded all data herself, always knowing which phase was in effect. A second observer checked agreement only in three A1 sessions (94%). What most limits confidence in this demonstration?

Accepted Answer

Possible observer bias, because agreement was never checked during treatment phases

Answer

Maturation, because Caleb's cursing changed over the weeks the evaluation ran

Answer

History, because an outside event may have coincided with the first phase change

Answer

Too little replication, because the effect appeared in only two treatment phases

Question 6

Kwame, a BCBA, uses a changing-criterion design to reduce how often Lena, 16, checks her phone during a one-hour homework period; she earns extra weekend screen time on days she stays at or under the limit. Checks per day: baseline 20, 22, 21, 20; limit of 15: 15, 14, 15; limit of 10: 10, 9, 10, 10, 9; limit of 15 again: 14, 15, 15; limit of 6: 6, 5, 6, 6. Do these data show experimental control, and why?

Accepted Answer

Yes, because checks settled at each limit and rose again when the 15 limit returned

Answer

Yes, because checks fell from about 21 in baseline to about 6 by the final phase

Answer

No, because the contingency was never withdrawn to bring checks back to baseline

Answer

No, because checks went up in the fourth phase instead of continuing to fall

Question 7

Farah, a BCBA, has shown that tokens exchangeable for tablet time increase the spelling words Ines, 11, practices at a learning center. To choose how many tokens to give, she runs three phases in order: 1 token per word, then 3, then 5 (at most 20 words per session). Words practiced: 1 token 6, 7, 8; 3 tokens 9, 10, 11; 5 tokens 12, 13, 14. Practice rises steadily from session to session, with no jump at phase changes. Which problem most limits the conclusion that more tokens produced more practice?

Accepted Answer

An order confound: values only increased over time, so the trend may reflect practice, not magnitude

Answer

A ceiling effect: practice at 5 tokens neared the session maximum and hid larger gains

Answer

Multiple-treatment interference: token values alternated, so each session's value affected the next

Answer

Statistical regression: practice started unusually low in the first phase and drifted back up

Question 8

Priya, a BCBA, will teach Kenji, 7, three social skills at his after-school program: greeting peers, asking to join a game, and taking turns. The skills are not expected to influence one another, and once learned they are unlikely to disappear. Which design best fits this situation?

Accepted Answer

A multiple baseline design across the three skills

Answer

A reversal design applied to all three skills at once

Answer

A changing-criterion design for each skill in turn

Answer

A single A-B design using one combined score for all three skills

BCBA Experimental Design practice questions

8 Experimental Design questions

Ready for a 20-question BCBA practice test?

BCBA Experimental Design practice questions

8 Experimental Design questions

Ready for a 20-question BCBA practice test?