Sampling method examples
I ask everyone in my stat's class their favorite color
Convenience
Each student at a school has a student identification number. Counselors have a computer generate 50 random identification numbers and those students are asked to take a survey.
Simple Random
Each student at a school has a student identification number. Counselors have a computer generate 50 random identification numbers, and the students associated with those numbers are asked to take a survey.
Simple Random
I want to find the weight of the fish in my pond. I assign every fish in the pond a number. I randomly select 10 fish and weigh them.
Simple Random
I want to figure out what stats students think of the class. I assign every student a number then pick 20 numbers out of a hat.
Simple Random Sampling
A school chooses 3 randomly selected athletes from each of its sports teams to participate in a survey about athletics at the school.
Stratified
A truck manufacturer selects 3trucks at random from each of 6 models for safety testing.
Stratified
I want to know the football team's opinion on the coach. I separate them into JV and Varsity and randomly sample 5 from each team.
Stratified
I want to figure out every DMC Highschool student's opinion on ILT. I separate them out by grade, then randomly select 10 students per grade
Stratified.
To sample the population of a major city, I separate the population into groups based on their race, then randomly select 50 people from each subgroup.
Stratified.
Employees at a website want to select a sample of their users to ask for a donation. They randomly select one of the first 25 user each day and show them a message asking for a donation. They also show the message to every 25th user from that point on.
Systematic
I ask every third member of the cross country team their preferred course.
Systematic
I pull every 1,000th twinkie off the line to test.
Systematic
Using the list of registered voters, I sample every 8th registered Republican to get their opinion on the president
Systematic
While students are lined up for school pictures, a teacher passes out a survey to every 10th student.
Systematic.
I ask random people on the street to take a survey about current events.
Voluntary
A restaurant leaves comment cards on all of its tables and encourages customers to participate in a brief survey to learn about their overall experience.
Voluntary Response
I email every student asking them to fill out a survey for yearbook.
Voluntary response
I want to know the opinions of every Chick-Fil-A employee in America. I randomly select 20 stores and then sample every employee in those stores.
cluster
A politician asks his neighbors their opinions about a controversial issue.
convenience
A store prints a request on each receipt asking customers to fill out a satisfaction survey online if they are willing.
convenience
A hospital wants to survey religious participants in their city about what they seek from a hospital chaplain, so they randomly select 5 religious meetings in the city and survey every participant in those meetings.
Cluster
A principal orders t-shirts and wants to check some of them to make sure they were printed properly. She randomly selects 2 of the 101 boxes of shirts and checks every shirt in those 2 boxes.
Cluster
An airline company wants to survey its customers one day, so they randomly select 555 flights that day and survey every passenger on those flights.
Cluster
I want to figure out the average weight of beef cows in Iowa. I randomly select 15 farms and weigh all the cows at each farm.
Cluster
To find out 8th grader's math ability, I randomly select 10 middle schools in Iowa then test every 8th grader's math ability.
Cluster
A quality control worker at a factory selects the first 10 items she sees as her sample for the day.
Convenience
I ask the people parked next to me what they think of carline.
Convince
I look at the roster of graphic design students and select every 4th student to sample.
Systemic