Sampling Definitions
Each member of the population has an equal chance of being chosen.
Simple Random Sampling
Students do not want to share their school grades
Privacy
Ifan rolls a fair dice, with sides labeled A, B, C, D, E and F. What is the probability that the dice lands on a vowel?
2/6 or 1/3
Asking the first 10 people you see
Convenience Sampling
Every nth member of the population is chosen
Systematic Sampling
The results of a survey on ski-jackets may differ if the survey is conducted in the summer instead of the winter
Timing
There are 4 red, 3 green, 2 blue and 5 black marbles in a bag. What are the chances of pulling a marble that starts with the letter B?
7/14 or 1/2
Split students up by grade and then only ask the grade 9 students what their favorite cafeteria food is
Cluster Sampling
Members of the population volunteer to be chosen
Self-Selected Sampling or Voluntary Sampling
A question about Christmas shopping may offend those who do not celebrate Christmas
Cultural Sensitivity
What is the probability of pulling a face card from a 52 card deck?
12/52 or 3/13
Split students up into grades and then randomly select 10 students from each grade and ask them what their favorite movie is
Stratified Random Sampling
Some members of each group of the population are randomly chosen
Stratified Random Sampling
A 30-minute Survey conducted over the lunch period may not interest students
Time
A sample of 50 people were asked what their favorite color was and 20 people answered red, how many people could we expect to answer red if the population was 250?
100
Ask every 10th person that walks by you on the street who they are voting for
Systematic Sampling
The population is divided into groups and every member of the group is chosen
Cluster Sampling
Don't you think cafeteria food is too expensive?
Use of Language
There are 18 girls and 12 boys in a class. 2/9 of the girls and 1/4 of the boys walk to school. One of the students who walks to school is chosen at random. Find the probability that the student is a boy.
3/7
Tell students you are conducting a survey at lunch on what their favorite food is
Self-Selected Sampling or Voluntary Sampling