In a study cited in the textbook, Schedlowski asked participants to drink green, lavender-scented strawberry milk. Half the participants took an immunosuppressive drug along with the milk. The remainder took a placebo pill. Five days later, and then again 11 days later, all participants took a placebo pill with the milk. Both times, Schedlowski measured the immune responses of all participants. In this study, immunosuppressive drug-vs.-placebo is the _____ variable.

Question

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The immunosuppressive drug is the independent variable because it is being manipulated by the researcher. The placebo and measurement of immune responses are both control variables that are held constant throughout the study. The dependent variable is the immune response, which is being measured and is expected to be influenced by the independent variable.

In a Study Cited in the Textbook, Schedlowski Asked Participants