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All courses Math III · S-IC.3 49 of 55
Distinguish sample surveys, experiments, and observational studies; explain randomization in each.

Recognize a sample survey

Problem
Is this study a sample survey: poll asks 800 adults their opinion, no treatment assigned?
Your answer
Show answer choicesAnswer choices Work through the mathematics first, then compare your reasoning.Select the answer that matches your work.
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Hint

Look for whether the study only asks people questions or actually assigns them to a treatment.

A sample survey gathers information from a sample without imposing a treatment.

Solution walkthrough

01

Identify what the study does

\[\text{Poll}~\text{asks}~800~\text{adults}~\text{their}~\text{opinion}\]

The study collects responses from people by asking questions.

02

Check for treatment assignment

\[\text{No}~\text{treatment}~\text{assigned}\]

The question explicitly says nothing was assigned or imposed on the adults.

03

Match the study type

\[\text{asking}~a~\text{sample}~\text{for}~\text{responses}~→~\text{sample}~\text{survey}\]

This is the defining feature of a sample survey.

04

State the classification

\[\text{Classification}:~\text{sample}~\text{survey}\]

Because the researchers only asked \(800\) adults for their opinions, this study is a sample survey.

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Another way

  1. Use a quick test: if subjects are only asked or measured and no treatment is imposed, think survey or observational study, not experiment.

!

Common mistake

Calling it an experiment just because data were collected, even though no treatment or assignment happened.