Algebra 1 Common Core Student Edition, Grade 8-9

Name Sa m p l i n g M e t h o d Ex a m p l e

Random Survey a population at random. Survey people whose names are

drawn out of a hat.

Systematic Select a number n at random. Then

survey every nth person.

Select the number 5 at random.

Survey every fifth person.

Stratified

V

Separate a population into smaller

groups, each with a certain

characteristic. Then survey at random

within each group.

Separate a high school into four

groups by grade level. Survey a

random sample of students from

each grade.

. - ... _

Pr o b l em 3

What p opulat ion
are you t rying t o
represent with this
sam p l e?
You w ant to collect
information about the
students a t your school.

Ch o o sin g a Sam p le

DVD Ren t al s You want to find out how many DVDs students at your school rent in a

month. You interview every tenth teenager you see at a mall. What sampling method

are you using? Is this a good sample?

Since you are interviewing every tenth teenager, this method is systematic. This is not a

good sample because it will likely include teenagers who do not attend your school.

Go t I t? 3. You revise your plan and interview all students leaving a school

assembly who are wearing the school colors. Will this plan give a

good sample? Explain.

A survey question has b i as when it contains assumptions that may or may not be true.

Bias can influence opinion and can make one answer seem better than another. Survey

questions must be carefully worded to avoid bias.

Pr o b l em 4 Determ ining Bias in a Survey Question

Movies A reporter wants to find out what kinds of movies are most popular with

local residents. The reporter asks, "Do you prefer exciting action movies or boring

documentaries?” Is the question biased? Explain.

The survey question To determine Check the question for adjectives

w hether the question or phrases th a t make one category

is biased seem more appealing.

The question is biased because the words exciting and boring make action films sound

more interesting than documentaries.

Go t It? 4. Reasoning How can the question in Problem 4 be reworded so that

it is not biased?

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Po w erAlg eb ra.com Lesso n 12-5 Sam p les an d Surveys 755