AP STATISTICS
Quiz on Samples, Bias, & Survey Design
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Skittles would like to check the color distribution in their bags of candy. Would a census or sampling be used?
Sampling
The LTHS freshman class president is elected. Would a census or sampling be used?
Census
You want to estimate the average number of TV sets per household in your community of 12,500 people.
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What is the population of interest?
All households in my community
Explain the advantages of sampling over conducting a census in this situation.
Sampling would be quicker, easier, and cheaper. Sampling does not require me to get ahold of every single household in
my community.
For each of the following, state whether the study described is observational or experimental.
State any problems that you see with the design if any.
Identify the explanatory variable (if there is one), response variable, and describe how a possible confounding variable might affect
the results if applicable.
5. Sally would like to know if drinking coffee before playing a musical instrument changes your timing. She has all of her
friends in band play a piece of music and times it and then has them drink a cup of coffee and then play the same piece and
times it and compares the times.
Experimental
There is a problem with her sampling method since it seems to just be a convenience sample since she is only choosing her
friends for the experiment. She should do a simple random sample of the entire band to reduce bias or any problems.
The explanatory variable is drinking coffee.
The response variable is the timing of playing a piece of music.
A possible confounding variable could be if they are tired of playing the same piece of music, then they may play it quicker
just to get it over with.