Sampling: SAMPLING METHODS Simple Random Sample: Stratified Sample: Systematic Sample:

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1 Name: Date: Hour: Unit 9 Statistics Sampling and Sampling Bias Notes By the end of this lesson, students will be able to Identify different types sampling. Identify different types of sampling bias. Statistics: Sampling: SAMPLING METHODS Simple Random Sample: Stratified Sample: Systematic Sample: Example 1: Identify the type of sampling in each of the following examples. a. A group of lobbyists has a list of the 100 senators of the United States. To determine the Senate s position regarding farm subsidies, they decide to talk with every seventh senator on the list, starting with the third.

2 b. Josh wants to know how households in his neighborhood feel about Michigan weather. He numbers all the houses in his neighborhood and then randomly generates 24 numbers using his calculator and interviews people in those households. c. Tim wants to know if different grade levels feel differently about school spirit. He separates students by grade, then numbers the students in each grade and randomly selects 30 students from each grade to give a questionnaire about school spirit. Sampling Bias: Convenience Sampling: Voluntary Response Sampling: Example 2: Identify the type of sampling bias in each of the following examples. a. David wants to know what people think of the judges on American Idol. He asks his friends and neighbors their opinions of the judges. b. A restaurant wants to know if they are providing good service to their customers. To try to gather opinions, they print a survey at the bottom of every receipt asking for customers to call in with their opinions of the restaurant service.

3 Name: Date: Hour: Sampling and Sampling Bias Quick Check 1. Identify the type of sampling used: 24 Hour Fitness wants to administer a satisfaction survey to its current members. Using their membership roster, the club randomly selects 40 club members and asks them about their level of satisfaction with the club. 2. Identify the type of sampling bias: A local radio station wants to know the opinions of its viewers when it comes to US peacekeeping in the Middle East. The radio station asks listeners to call in with their views. Self-Assessment Learning Goals Identify different types of sampling. I am unsure of or confused about this I am ready to start practicing I am already good at this Identify different types of sampling bias. My Goals for Today- thinking about what I am good at, where am I confused and what do I need to work on? What do I do if I am confused or need to work on a learning target?

4 Name: Date: Hour: Unit 9 Sampling and Sampling Bias Homework Identify the type of sampling used. Statistics 1. To estimate the percentage of defects in a recent manufacturing batch, a qualitycontrol manager at Intel selects every 8 th chip that comes off the assembly line starting with the 3 rd until she obtains a sample of 140 chips. 2. A member of Congress wishes to determine her constituency s opinion regarding estate taxes. She divides her constituency into three income classes: low-income households, middle-income households, and upper-income households. She then takes a simple random sample of households from each income class. 3. In an effort to identify if an advertising campaign has been effective, a marketing firm conducts a nationwide poll, randomly selecting individuals from a list of known users of the product. 4. A school official divides the student population into classes: freshman, sophomore, junior, senior, and graduate student. The official takes a simple random sample of each class and asks the members opinions regarding student services. 5. A small-town newspaper reporter wants to get local reaction to a controversial new film. She waits outside the theater during an afternoon show and, starting with the second, asks every fifth patron leaving how much they liked the movie. 6. A statistics instructor with a large number of students, attempts to reduce time spent grading by only grading a portion of assigned homework problems. He randomly selects one of the first four problems in the assignment and then grades that problem and every fourth problem thereafter.

5 Is there sampling bias in each of the following examples? If so, identify which type of sampling bias it is. 7. Sarah wants to know how Michigan residents feel about the show The Voice. She interviews her friends at school and her neighbors. 8. Drew wants to know what seniors plan to do after they graduate. He interviews the seniors in his ceramics class. 9. Applebee s wants to know how their customers feel about their menu. They put a survey attached to each receipt. 10. Stacey wants to know how her Algebra I classmates feel about school spirit. She has every student in her class complete a survey. 11. John wants to know how geometry students feel about the show American Idol. He asks each person in his class period to complete a survey. 12. Amanda wants to know how calculus students feel about The Voice. She asks each person in all of the calculus courses to complete a survey. 13. Bell Tire wants to know how their customer satisfaction is. They send out an to their customers asking them to complete an online survey. 14. Sally wants to know how students feel about the lunch-room menu. She makes an announcement at lunch for students to come and complete a survey.