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Dr. Kim is conducting an experiment investigating the relationship between drinking coffee and alertness. In this experiment, she randomly assigns participants to one of two groups--caffeinated coffee or decaffeinated coffee and then rates their alertness. According to the "Research Designs" reading, if Dr. Kim knows who is in which group and expects the coffee group to be more alert, what effect is this MOST likely to have on the results?

a) It will have no effect on the results.
b) It will increase the reliability of the results.
c) It may introduce experimenter bias and affect the results.
d) It will enhance the external validity of the study.

User Ataraxic
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Final answer:

Dr. Kim's knowledge of who is in which group could introduce experimenter bias into the experiment's results. A double-blind study would be the most suitable method to avoid such biases and validate the effects of caffeine on alertness objectively.

Step-by-step explanation:

If Dr. Kim knows who is in which group in the experiment and expects the caffeinated coffee group to be more alert, this may introduce experimenter bias and affect the results. Experimenter bias occurs when a researcher's expectations influence the outcomes of a study. For instance, Dr. Kim might unconsciously rate the alertness of participants drinking caffeinated coffee higher due to her expectations. To minimize this effect, it is essential to conduct a double-blind study, where neither the participants nor the researchers know who belongs to the control or experimental groups. This method reduces the influence of both experimenter and participant expectations that can lead to a placebo effect, where simply expecting a change can cause that change to happen.

In well-designed research, random assignment and control groups are used to eliminate confounding variables, ensuring that the only difference between the treatment groups is the one imposed by the researcher. This means that if the groups respond differently, the difference can be attributed to the effect of the substance being tested, in this case, caffeine.

User Wonsuc
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