Honors Advanced Algebra Presentation 1-3 Sampling Methods Honors Advanced Algebra Presentation 1-3

Essential Question and Standards EQ: How do I determine if my sampling method is unbiased? MCC9-12.S.IC.3 Recognize the purposes of and differences among sample surveys, experiments, and observational studies; explain how randomization relates to each

Vocabulary Sample – a portion of the population. Population – the entire group that is being studied. Statistic – a number that describes a sample. Parameter – a number that describes the population. Survey – a study of a sample of the population used to predict characteristics of the entire population. Census – a study of the entire population.

Biased vs unbiased samples Unbiased sample - a random sample that is representative of the population. Underrepresented sample – a sample where one or more groups of the population are omitted. Overrepresented sample – a sample where one or more groups has a greater representation than in the general population.

Types of Samples Name: Random Sample Method: Every member of the population has an equal likelihood of being chosen. Examples: Assign everyone a number and have a random number generator pick numbers. OR Put every person’s name in a hat and pick out names.

Types of Samples Name: Systematic Sample Method: Pick sample participants based on a rule. Examples: Choose every 5th person who walks through the door. OR Ask everyone whose last name begins with M.

Types of Samples Name: Convenience Sample Method: Pick sample participants based on who is available. Examples: Choose the first 10 people you see when you enter your next class. OR Choose the friends that you are meeting after school.

Types of Samples Name: Self-Selected Sample Method: Participants choose to be included in the sample Examples: Put out a survey at the front desk for guests to fill out. OR Offer shoppers a discount for going online to answer a survey.

Types of Samples Name: Stratified Random Sample Method: The population is divided into groups. Each member of each group has an equal chance of being chosen. Examples: Choose 10 males and 10 females to participate. OR Choose 20 people born in each decade from 1950-2009.

Sample or population? What is the population and what is the sample? A car factory just manufactured a load of 6,000 cars. The quality control team randomly chooses 60 cars and tests the air conditioners. They discover that 2 of the air conditioners do not work. Population: 6,000 cars Sample: 60 cars

Sample or population? What is the population and what is the sample? In a survey of 40 employees at a company, 18 said they were unhappy with their pay. The company has 180 employees. Population: 180 employees Sample: 40 employees

Biased or unbiased? Type of Sample? Call 100 random people listed in the phone book to ask how long they’ve been living in their home: , Ask every 10th person at a school off of a complete roster about how many courses they are taking: , Ask 25 families eating at a restaurant on a Tuesday night about how often they eat out: , Out of each class at school, ask a number of students proportional to the number of students in each class how much they enjoyed homecoming: , Biased Random Sample Unbiased Systematic Sample Biased Convenience Sample Unbiased Stratified Random Sample

Homework Pg. 20-21, #14-25