6th Grade Math Textbook, Progress

Bias in Surveys

9-3

When you collect data in a survey, your sample should represent

the whole population. If certain groups from the population are not

represented in the sample, then the sample is a biased sample.

To determine which sports television programs are the most popular in

a city, a survey is made by selecting and interviewing people at random

on a street corner. Outside of which location would the interviewer be

most likely to find a biased sample? Explain.

A.a sports arena B.a concert hall C.a park

Sample from A is most likely to be biased in favor of sports programming.

Sometimes, questions are biased. A biased question suggests or

leads to a specific response or excludes a certain group.

Roger and Gino want to find out the favorite spectator sports of the students

in school. Roger asks, Don’t you think soccer is the most fun sport to watch?

Gino asks, Which sport do you think is the most fun to watch?

Whose question is biased?

Roger’s question is biased toward soccer.

Data displays can be biased and influence how results are interpreted.

Look at these graphs.

Shoe sales appear to be lower in summer than in fall. Look carefully at

the intervals on the vertical axes and you will see that is not true.

June July Aug.

250

200

150

100

50

0

Pairs of Shoes

Month

Summer Shoe

Sales

Sept. Oct. Nov.

50

40

30

20

10

0

Pairs of Shoes

Month

Fall Shoe

Sales

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