Chapter 1.1, Problem 1.18E

a)

To determine

To identify whether the observational study or experimental study.

Answer to Problem 1.18E

This is an experimental study.

Explanation of Solution

Given:

In an effort to make their teeth whiter, some people use whitening strips or bleaching gels. Are new "light-activated bleaching techniques" any more effective? Researchers carried out a study to help answer this question. They gathered a small group of dental patients who were willing to participate. On one side of patients' mouths, the researchers used bleaching gel alone. On the other side, they used light plus bleaching gel. The results? The patients' teeth got whiter on both sides of their mouths; there was no real difference in whiteness between the two sides.

First need to understand about the experimental study and observational study:

Experimental study: Assigning people or things to groups and applying some treatment to one group, while the other group does not receive the treatment.

Observation study: In an observational study, measure or survey members of a sample without trying to affect them.

This study is an experimental study. The part of the patient’s mouth were deliberately treated different than the other part of the patients mouth.

b)

To determine

To explain why the researchers apply both possible treatments to each patient, rather than using bleaching gel on only half of the patients and light plus bleaching gel on the other half.

Explanation of Solution

Given:

In an effort to make their teeth whiter, some people use whitening strips or bleaching gels. Are new "light-activated bleaching techniques" any more effective? Researchers carried out a study to help answer this question. They gathered a small group of dental patients who were willing to participate. On one side of patients' mouths, the researchers used bleaching gel alone. On the other side, they used light plus bleaching gel. The results? The patients' teeth got whiter on both sides of their mouths; there was no real difference in whiteness between the two sides.

The researcher wants to know if the light affect the bleaching or not and in a different people affect of bleaching will differ or not. That’s why the researchers apply both possible treatments to each patient, rather than using bleaching gel on only half of the patients and light plus bleaching gel on the other half.