A study was conducted to see whether participants would ignore a sign that?said, "Elevator may stick between floors. Use the?stairs." Those who used the stairs were said to be?compliant, and those who used the elevator were said to be noncompliant. There were three possible?situations, two of which involved confederates. A confederate is a person who is secretly working with the experimenter. In the first?situation, there was no confederate. In the second?situation, there was a compliant confederate?(one who used the?stairs), and in the third?situation, there was a noncompliant confederate?(one who used the?elevator). The subjects tended to imitate the confederates. What more do you need to know about the study to determine whether the presence or absence of a confederate causes a change in the compliance of?subjects?

Select all that apply.

Select all that apply. I] A. Identify whether there was random assignment to groups. Without random assignment there is the possibility of bias, so we cannot infer causation. [I B. Identify the absence or presence of a placebo. Without a placebo, the treatment could be confounded by the participant's expectation of the treatment. [I C. Identify the sample size of the study. Without enough participants to observe the full range of variability in subjects we cannot control for other relevant factors, so we cannot infer causation. E] D. Identify the number of treatment groups. Without a sufciently large number of treatment groups there is insufficient variation in the study, so we cannot infer causation