6th Grade Math Textbook, Progress

Samples

9-2

For each survey question, tell whether you would

survey the populationor use asample. Explain.

1. What section of the newspaper do 2. Where do the students in your class
   subscribers read first? want to go on a field trip?


2. What is the most popular car of the 4. What is the favorite animal of
   people in your city? students in your school?


3. What is the favorite movie of the 6. Who is the favorite counselor of
   people working in the video store? the students at summer camp?

The entire group of individuals or objects considered for a survey is

called the population. If it is not practical to survey an entire population,

a small part of the population, called a sample, is used. A sample is

said to be a representative sample if it has characteristics similar to

the entire population.

John wants to find how many of 14,000 voters in a town are likely to vote for

Candidate A. Explain whether a survey of the population or a sample is better.

John should use a sample since it is not practical

to survey the entire population.

If the population changed to only 50 voters, John

can survey the population. Given time, each member

of the population could be surveyed individually.

There are different ways of selecting a sample:


Random sampling — Each individual or object in the given population

has an equal chance of being chosen. A representative sample can

be provided by random sampling.

Example: 50 voters whose names are chosen, without looking, from

a box containing all voters’ names.


Convenience sampling — Each individual or object is chosen because

they are available and accessible.

Example: The first 50 voters to arrive at a polling place are surveyed.


Responses to a survey — Each individual is given an oral interview or

written questionnaire.

Example: Some voters might mail completed survey forms to the researcher.

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