Question

Which of the following studies on the effectiveness of a new tooth whitening gel is NOT an experiment?A..B..C..D. A.

A dental practice sends coupons for the tooth whitening gel to all their patients. After two months, as patients come in for appointments, they are asked if they have used the product or not. The whiteness of patients’ teeth is assessed by a technician who does not know who used the gel, and users are compared with non-users

B. A group of 88 adults is divided at random into two groups. One group is given the tooth whitening gel and the other is given a similar-looking package of gel that has no whitening effect. Both groups are told to use their gel for 6 weeks. At the end of the period, the whiteness of their teeth is assessed by a technician who does not know which gel was used

C. A group of 88 adults has their teeth examined and the whiteness of their teeth is assessed using a dental scale. Then, patients who have teeth of similar whiteness are paired, and one member of each pair is given the whitening gel to use; the other person gets a “placebo” gel. At the end of 6 weeks, the whiteness of their teeth is assessed again assessed by a technician who does not know which gel was used, and it’s recorded if their teeth are still equally white or if one member of the pair now has a whiter shade

D. A group of 88 adults has their teeth examined and the whiteness of their teeth is assessed using a dental scale. The, all of them are given the whitening gel to use for 6 weeks. At the end of 6 weeks, the whiteness of their teeth is assessed again and, for each participant, it’s recorded if the whiteness of their teeth has changed.

Answer 1

The researcher has no control over the variables in an observational study. An experiment is a method of applying treatments to a group and recording the effects. That is, for an experiment, the researcher has control over the variables.

Option A - the study does not control if the patients use the tooth whitening gel product or not. Thus, this study is not an experiment.

Option B - One group is given the tooth whitening gel and the other is given a similar-looking package of gel that has no whitening effect. Thus, in the study, technician are applying treatments to a group and recording the effects and they have control over the variables. Thus, this study is an experiment.

Option C - One member of each pair is given the whitening gel to use; the other person gets a “placebo” gel. Thus, in the study, technician are applying treatments to a group and recording the effects and they have control over the variables. Thus, this study is an experiment.

Option D - All of them are given the whitening gel to use for 6 weeks. Thus, in the study, technician are applying treatments to a group and recording the effects and they have control over the variables. Thus, this study is an experiment.

Hence, the correct option is A.