Warm Up For each situation, explain whether it makes sense to use a sample.

1. Warm Up For 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.

2. Common Core State Standards Learning Objective 7.SP.1 Determine how statistics can be used to gain information about a population.

3. Vocabulary systematic sample convenience sample self-selected sample

4. Recall 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.

5. Additional Example 1: Identifying Sampling Methods The manager of a company wants to know how many employees have a laptop computer at home. Identify each type of sampling method. 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.

6. Check It Out! Example 1 You want to know how often students in high school take tests. Identify each type of sampling method. 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.

7. Random samples and systematic samples are more likely to be representative of a population than either convenience samples or self-selected samples.

8. Additional Example 2: Analyzing Sampling Methods Determine which sampling method will better represent the entire population. Justify your answer. Jon’s sample is a random sample, giving every band member an equal chance to be surveyed, so it is the better method.

9. Check It Out! Example 2 Determine which sampling method will better represent the entire population. Justify your answer. Ferdinand’s method produces results that better represent the entire swimming team population.

10. Lesson Quiz 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. convenience sample self-selected sample systematic sample

11. Classwork & Homework Lesson 7-7 Practice Lesson 7-7 Problem Solving