A researcher is interested in the effects of watching videos just before bed on the quality of
sleep. He has decided to test the claim "Watching 1 hour of video just before going to bed
reduces the number of minutes of
...
A researcher is interested in the effects of watching videos just before bed on the quality of
sleep. He has decided to test the claim "Watching 1 hour of video just before going to bed
reduces the number of minutes of REM sleep by more than 10%." How should the number of
hours of video be treated?
The number of hours of video should be controlled. Some measurements should be
done for 1 hour of video and some should be done with no video.
The number of hours of video is an experimental factor that needs to be controlled. The
claim specifies 1 hour. So there should be a test set for people who watched 1 hour of
video and a control set for people who watched no video.
In a survey conducted to find out the feedback of a sports program organized in a club, the
organizers asked the respondents to classify their feedback as good, fair, poor, and bad. Is the
study observational or experimental? If it is an experiment, what is the controlled factor?
The study is an observational study.
The samples are chosen using an appropriate process; however, no attempt is made to
control any aspect of the sample even though the variables of interest are recorded for
each group
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