1. In a(n) ____________, only the participants of the experiment do not know whether they are in the experimental group or the control group.
2. In an experiment, the ___________ includes the participants who are not exposed to experimental variables.
3. The ________ is a change in a patient’s physical state that results from the patient’s perceptions of the treatment.
4. In a(n) ___________, neither the participants nor the experimenter knows whether the participants are in the experimental group or the control group.
5. Researchers generally select a(n) __________, which is a relatively small group of the total population that is being studied.
6. In a (n) _________, a researcher studies a group of people over a period of years.
Key:1d; 2c; 3f; 4e; 5a; 6