IXL - Experiment design (Algebra 1 practice)

Read the following description of an experiment.

Space program scientists would like to provide fresh fruits and vegetables for astronauts in orbit. However, they are concerned that fresh produce may not survive the radiation levels of space. As a result, they commission a study to test the effects of radiation on the shelf life of an apple.

The researchers randomly select 40 apples and store them under high levels of radiation. They record how long it takes for the apples to spoil.

Is this experiment statistically well designed?

yes

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question

Read the following description of an experiment.

A cleaning supply company is concerned that its new ultra-shine wax makes floors too slippery. Company scientists are conducting an experiment to see how safe the new wax is.

The scientists randomly organize subjects into two groups. They ask 50 subjects in the first group to walk on a floor with the new wax. They ask 50 subjects in the other group to walk on a floor with an old wax. They then record how often each subject slips.

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 ultra-shine wax.

The company scientists randomly organize the subjects into two groups. The treatment group walks on a floor with the new wax, while the control group walks on a floor with an old wax.

Since the experiment has a treatment group and a control group, and both groups were randomly chosen, the experiment is statistically well designed.

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II.1Identify biased samples

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