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Holt CA Course Selecting Samples SDAP2.2 Identify different ways of selecting a sample (e.g., convenience sampling, responses to a survey, random sampling) and which method makes a sample more representative for a population. California Standards
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Holt CA Course 1
7-7 Selecting Samples
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Holt CA Course 1
7-7 Selecting SamplesWarm UpFor each situation, explain whether it makes sense to use a sample.1. You want to know the most popular TV show
among teenagers in Los Angeles.
2. You want to know the favorite composer of the music teachers at a small college.
3. The editor of a newspaper wants to know the average age of the newspaper’s readers.
Yes; the population is large.
No; the population is small.
Yes; the population is large.
Holt CA Course 1
7-7 Selecting Samples
SDAP2.2 Identify different ways of selecting a sample (e.g., convenience sampling, responses to a survey, random sampling) and which method makes a sample more representative for a population.
California Standards
Holt CA Course 1
7-7 Selecting Samples
Vocabularysystematic sampleconvenience sampleself-selected sample
Holt CA Course 1
7-7 Selecting SamplesRecall that in a random sample each member of the population has an equal chance of being selected. Some other types of sampling methods are described below.
Sampling MethodsMethod Description
systematic sample A member of the population is selected at random, and then others are selected by using a pattern.
convenience sample The most-available members of the population are chosen.
self-selected sample Members of the population volunteer to respond to a survey.
Holt CA Course 1
7-7 Selecting Samples
Random samples and systematic samples are more likely to be representative of a population than either convenience samples or self-selected samples.
Holt CA Course 1
7-7 Selecting Samples
The manager of a company wants to know how many employees have a laptop computer at home. Identify each type of sampling method.
Additional Example 1: Identifying Sampling Methods
A. The manager randomly chooses 40 names from a list of all employees.This is a random sample because every employee has an equal chance of being selected.
B. The manager surveys the first 50 employees as they arrive at the office.This is a convenience sample because the group of employees is easy to reach.
C. The manager places a stack of survey forms in the company cafeteria.This is a self-selected sample because the group of employees chooses whether to complete the surveys.
Holt CA Course 1
7-7 Selecting Samples
Determine which sampling method will better represent the entire population. Justify your answer.
Additional Example 2: Analyzing Sampling Methods
Jon’s sample is a random sample, giving every band member an equal chance to be surveyed, so it is the better method.
Band Uniform StyleSampling Method ResultsMaria surveys only the band students she knows personally.
84% want blue uniforms
Jon writes each band student’s name on a card. He questions those students whose name he draws.
61% want blue uniforms
Holt CA Course 1
7-7 Selecting Samples
You want to know how often students in high school take tests. Identify each type of sampling method.
Check It Out! Example 1
A. You survey the first 50 students as they arrive at school.This is a convenience sample because the group of students is easy to reach.
B. You place a stack of survey forms in the student library.This is a self-selected sample because the group of students chooses whether to complete the surveys.
C. You randomly choose 40 names from a list of all students and then every 5th name after that.This is a systematic sample because the students are chosen at random and then the other names are chosen by using a pattern.
Holt CA Course 1
7-7 Selecting Samples
Determine which sampling method will better represent the entire population. Justify your answer.
Check It Out! Example 2
Ferdinand’s method produces results that better represent the entire swimming team population.
Swimming SchedulingSampling Method ResultsFerdinand surveys every other swimmer on the team.
72% want practice early
Anna-Maria questions the swimmers who are in her Biology class.
50% want practice early
Holt CA Course 1
7-7 Selecting Samples
An eye doctor wants to know how many of her patients work at a computer. Identify each type of sampling method.1. The doctor surveys the patients in the waiting
room one morning.
2. The doctor places cards in the waiting room.
3. The doctor chooses every 50th name from a database of her patients.
Lesson Quiz
convenience sample
self-selected sample
systematic sample
