7th Grade Math

Multi-Part

Lesson (^3) Predictions
PART A BCDEF
Multi-Part
Lesson 3
Get ConnectED
GLE 0706.5.3
Formulate questions and
design studies to collect data
about a characteristic shared
by two populations, or
different characteristics
within one population.
GLE 0706.5.5 Understand
and apply basic concepts of
probability. Also addresses
GLE 0706.1.7.
472 Probability and Predictions
Unbiased and Biased
Samples
ENTERTAINMENT The manager of a
television station wants to conduct a
survey to determine which sport people
consider their favorite to watch.

1. Suppose she surveys a group
   of 100 people at a basketball
   game. Do the results represent
   all of the people in the viewing
   area? Explain.


2. Suppose she surveys 100 students
   at your middle school. Do the results
   represent all of the people in the
   viewing area? Explain.


3. Suppose she calls every 100th household in the telephone book.
   Do the results represent all of the people in the viewing area?
   Explain.

The manager of the television station cannot survey everyone in the

viewing area. To get valid results, a sample must be chosen very

carefully. An unbiased sample is selected so that it accurately

represents the entire population. Two ways to pick an unbiased

sample are listed below.

Unbiased Samples

Type Description Example

Simple

Random

Sample

Each item or person in the

population is as likely to be

chosen as any other.

Each student’s name is

written on a piece of paper.

The names are placed in a

bowl, and names are

picked without looking.

Systematic

Random

Sample

The items or people are

selected according to a

specific time or item

interval.

Every 20th person is chosen

from an alphabetical list of

all students attending a

school.

Main Idea

Predict the actions of a

larger group by using a

sample.

Vocabulary

unbiased sample

simple random sample

systematic random

sample

biased sample

convenience sample

voluntary response

sample

What Type of Sports

Do You Like to Watch?

Baseball

Basketball

Football

Lacrosse

Soccer

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