# Whether the given study is observational or designed experiment and the reason.

Whether the given study is observational or designed experiment and the reason.
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Layton
Justification:
Observational Study: An observational study measures the values of a variable without influencing the values of response variables and explanatory variables. Thus, in observational study, researchers can observe the behaviors of the individuals without influencing the outcome of that study.
Designed experiment: In a designed experimental study, researchers allocate individuals to a certain group under study and change the values of an explanatory variable intentionally, after which, the values of the response variable for each group is recorded.
All the teeth are divided into four treatment groups where researchers can observe the behaviors of the individuals with an attempt of influencing the outcome of this study.
Thus, it is not an observational study.
All the teeth are divided into four groups. Each tooth is randomly assigned to one of four treatments: gum A, gum B, gum G, or saliva. Each tooth group is placed into a device that simulated a human chewing gum. There is an attempt to influence the individuals as the value of explanatory variable is influenced and controlled by-researthers under study.
Thus, the given study is a designed experiment.