When does a child usually walk alone?

More specifically, a reinforcer is a consequence that _____ a behavior and _____ the probability of that behavior. A punisher is a consequence that ____ a behavior and _____ the probability of that behavior.

Fill in the blank(s) with the appropriate word(s).

The advantage of including two treatment groups receiving the treatment at different times in a replicated interrupted time series design is that

a. the control group is not necessary. b. the effect of a possible history threat to internal validity is more apparent. c. you avoid have to engage in pretest-posttest measurements. d. you can use counterbalancing to avoid maturation problems.