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Population and Sample

Population and Sample

Author: Al Greene
Description:

This packet should:
-Introduce the terms population and sample
-Discuss why we need to use samples
-Show examples of what samples and populations are

This packet talks about populations and samples, specifically what a representative sample is, why we use sampling, and what the difference between finite and infinite populations are.

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Tutorial

New Terms and Concepts

At this point, you should be familiar with basic math terms, such as addition and subtraction.

This packet introduces the concepts of:

  • Population
  • Sample
  • Representative Sample
  • Infinite vs. Finite

Source: Greene

Population and Sample

This powerpoint talks about population and sample, and why we need to use samples in the first place.

Source: Greene

Sample vs. Population

This is a video on the difference between sample and population, and how we use the sample to make inferences about the population.

Source: kahnacademy

Decide what is the sample, and what is the population

Suppose we are interested in the shoe size of all major league baseball players. We measure the shoe size of 5 baseball players from every team.

What is the sample? Do you think it is representative of the population?

What is the population? Is it finite(countable) or infinite?

 

We are interested in the spending habits of women who shop at a certain mall on Sundays. We would like to know how much money they usually spend on Sundays. One Sunday, we randomly ask 20 women throughout the day how much they have spent.

What is the sample? Do you think it is representative of the population?

What is the population? Is it finite(countable) or infinite?

 

We are interested in the average price of all new cars. We go to a Mercedes dealership and select 10 different cars and record the price for each one.

What is the sample? Do you think it is representative of the population?

What is the population? Is it finite(countable) or infinite?

Source: Greene

Answers

1) The sample is the 5 major league baseball players from each team. It seems like this would be representative, since we took a few players from every team.

The population is all major league baseball players. Since there is a set number of roster spots on a baseball team, and 30 MLB teams, this is a countable population.

 

2) The sample is the 20 women that were asked how much they spent that day. This would be representative, since the women were chosen at random throughout the day..

The population is all women who go shopping at that mall on Sundays. Not just any day of the week, but specifically Sundays. This would be finite, since there are only a certain number of people who go to that mall on Sundays.

 

3) The sample is the 10 cars chosen at the dealership. This is not representative, since the price of a new Mercedes is much higher than the price of other new cars.

The population is all new cars. This would be infinite, since there are always new cars coming off the line, and you would not be able to know exactly how many new cars are out there.

Source: Greene