This document discusses different types of sampling methods used in surveys: convenience samples are those easily accessible to researchers; self-selected samples involve volunteers; systematic samples select every nth participant; and random samples give all participants an equal chance of selection. It provides examples of each type, noting whether samples are likely biased, and how margin of error relates to sample size and population estimates.

1. 10.2 sampling.notebook March 26, 2013
Write down the definitions for the types of sampling.
convenience sample:
self­selected sample:
systematic sample:
random sample:

2. 10.2 sampling.notebook March 26, 2013
Employees who go to a company health fair are given survey cards that ask for
1.
opinions about new health­related programs. Those who fill out and return a
card are given a coupon for a free "Healthy Habits" lunch at the company
cafeteria.
a) Is this sample ­ convenience, self­selected, systematic, or random.
Explain your reasoning.
b) Tell whether this method is likely to result in a biased sample. Explain.

3. 10.2 sampling.notebook March 26, 2013
2. You plan to conduct a survey about the hobbies of students in your grade.
You have a list of the names of all 240 students in your grade. Describe
two ways you can choose a random sample of 30 students to survey.
736.0015
736.2316
736.5123
736.6047
736.5555
736.4212

4. 10.2 sampling.notebook March 26, 2013
3. Even a random sample can give a biased result just by chance. The margin of
error of a sample tells you how close you can expect a measure in a population
to be a measure found using a random sample taken from the population.
Margin of error = ±
1
√n

5. 10.2 sampling.notebook March 26, 2013
4. In a random survey of 1600 workers in a city, 47.5% say that it takes
them more than 30 minutes to get from home to work every day.
a) What is the margin of error?
b) Give an interval that is likely to contain the actual percent of all the city's
workers who take more than 30 minutes to get to work.