IXL - Experiment design (Precalculus practice)

Read the following description of an experiment.

Engineers at a tire manufacturer are concerned that their tires blow out too easily. The engineers are testing a new coating to see if it will make the tires more durable.

The engineers coat 500 randomly selected tires but do not coat 500 other randomly selected tires. They measure the durability of all 1,000 tires with a stress test.

Is this experiment statistically well designed?

yes

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Learn with an example

question

Read the following description of an experiment.

Medical data shows it can take more than 4 months to recover from knee replacement surgery. A team of researchers is conducting an experiment to see if a new rehabilitation program can help reduce this time.

The researchers ask 100 randomly chosen knee replacement patients to use the new program. They then note the recovery time for each patient.

Is this experiment statistically well designed?

yes

key idea

An experiment can be used to test the effectiveness of a treatment. It is statistically well designed if:

its subjects are randomly sorted into two groups: a treatment group and a control group
the subjects in the treatment group receive the treatment
the subjects in the control group do not receive the treatment

The subjects do not have to be randomly chosen from a population, but it is better if they are.

There are many other important design considerations for experiments, including ethical ones.

solution

The treatment in this experiment is the new rehabilitation program.

All 100 patients use the new rehabilitation program, so all 100 of them are in the treatment group. In a statistically well designed experiment, some of the subjects would be in a control group.

Since the experiment has no control group, it is not statistically well designed.

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