Samples

Samples & Surveys

4-1

Warm-Ups

1. 21 - 2(3)

2. 4 + 3 * 9

3. 2(9) + (3)

4. 6(1.4) + 12

5. 7(2.9) - 5

Vocabulary

populationsamplebiased samplerandom samplesystematic samplestratified sample

The population is the entire group being studied. The sample is the part of the population being surveyed.

A biased sample means it is not good representation of the sample. (Unfair)

Identifying Biased Samples

Identify the population and sample. Give a reason why the sample could be biased. a. A radio station choose 1500 people from the local phone book to survey about their listening habits.

Population Sample Possible Bias


b. An advise columnist asks her readers to write in with their opinions about how to hang the toilet paper on the roll.



c. Surveyors in a mall choose shoppers to ask about product preferences.


To get accurate information, it is important to use a good sampling method. In a random sample, every member of the population has an equal chance of being chosen. A random sample is best, but other methods are often used for convenience.

Sampling Method How members are chosen

Random By chance

Systematic According to a rule or formula

Stratified At random from randomly chosen subgroups

Identifying Sampling Methods

Identify the sampling method used:

a. An exit poll is taken of every tenth voter.

b. In a statewide survey, five countries are randomly chosen and 100 people are randomly chosen from each country.c. Students in a class write their names on strips of paper and put them in a hat. The teachers draws 5 names.

Lesson Quiz:

Identify the population and sample. Give a reason why the sample could be biased.1. A high school principal asks the first three people who leave the school play whether they liked it.


Lesson Quiz cont...

Identify the sampling method used.

2. At a baseball game, 10 sections are chosen at random and 10 random people from each section are polled.

3. A telemarketer calls the people that have a last name beginning with H.

Documents

Samples