Determine whether the following study is an observational st

Determine whether the following study is an observational study or an experiment.

(a) Seventh grade students are randomly divided into two groups. One group is taught math using traditional method; the other is taught math using a new method. After one year, each group is given an achievement test to compare proficiency.

(b) Conservation agents netted 250 large-mouth bass in a lake and determined how many were carrying parasites.

(c) While shopping, 200 people are asked to perform a taste test in which they drink from two randomly placed, unmarked cups. They are then asked which drink they prefer.

(d) A survey is conduced asking 400 people, “Do you prefer Coke or Pepsi?”

Solution

a)

Experiment, because we have an involvement in the behavior of the sample (we taught them in two different ways. [ANSWER, EXPERIMENT]

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b)

OBSERVATION, as they simply collected a sample and observed a certain characteristic.

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c)

EXPERIMENT, as we have an involvement in the behavior of the sample, blinding the brands in the taste test.

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d)

OBSERVATION, as we simply gathered data.