1. 2.3 Sampling Techniques Terms  Population: refers to all individuals who belong to a group being studied

2. 2.3 Sampling Techniques Terms  Population: refers to all individuals who belong to a group being studied  Sample: a group or items selected from the population

3. Example 1 Identify the Population in each survey question below How many scars did monkeys get who live in Africa that is dominated by lions?

4. Example 1 Identify the Population in each survey question below How many scars did monkeys get who live in Africa that is dominated by lions? Population -> monkeys in Africa

5. Example 1 Identify the Population in each survey question below How many scars did monkeys get who live in Africa that is dominated by lions? Population -> monkeys in Africa Do students prefer robot teachers or human teachers? This is real debate with regards to teachers of English in Asia.

6. Example 1 Identify the Population in each survey question below How many scars did monkeys get who live in Africa that is dominated by lions? Population -> monkeys in Africa Do students prefer robot teachers or human teachers? This is real debate with regards to teachers of English in Asia. Population -> students

7. More terms  Sampling frame : the group actually have a chance of being selected

8. More terms  Sampling frame : the group actually have a chance of being selected  Simple random sample : a sample in which every member of the population has an equal and independent chance of being selected

9. More terms  Systematic sample : a sample selected by listing a population sequentially and choosing members at regular intervals interval = population size / sample size

10.  Systematic sample example  interval = pop. of 100/ sample of 20 = every 5 th person surveyed

11.  Stratified sample : a sample in which each group is represented in the same proportion as it appears in the population

12.  Stratified sample : a sample in which each group is represented in the same proportion as it appears in the population i.e., Survey TPS students if they like the i-Phone. Note that there are more gr. 12s than gr. 8s so they should represent more of the survey.

13. Method  Stratified sample : So you choose to survey a fraction of each group within the sample to ensure each group is represented.

14. Method  Stratified sample : Choose a fraction with justification, say 30%. Grade# of StudentsRel. FrequencyNumber Surveyed 8120.05 9320.13 10470.19 11690.29 12780.33 Total2381

15. More terms  Stratified sample : Choose a fraction with justification, say 30%. Grade# of StudentsRel. FrequencyNumber Surveyed 8120.05 3 9320.13 9 10470.19 14 11690.29 20 12780.33 23 Total2381 69

16. More Sample Types

17.  Cluster sample - the total population is divided into groups (or clusters) and a simple random sample of the groups is selected.

18.  Cluster sample - the total population is divided into groups (or clusters) and a simple random sample of the groups is selected. Example: a fast-food chain could save time and money by surveying all its employees at randomly selected locations instead of surveying randomly selected employees throughout the chain

19.  Cluster sample - the total population is divided into groups (or clusters) and a simple random sample of the groups is selected.  Multi-stage sample – several levels of ran. Sampling

20.  Cluster sample - the total population is divided into groups (or clusters) and a simple random sample of the groups is selected.  Multi-stage sample – several levels of ran. Sampling Example: To examine Ontario households, you can randomly survey certain cities, then randomly survey random blocks, and then survey random houses.

21. Sample Types  Cluster sample - the total population is divided into groups (or clusters) and a simple random sample of the groups is selected.  Multi-stage sample – several levels of ran. sampling  Voluntary-response sample – researcher invites any member of population into survey

22.  Cluster sample - the total population is divided into groups (or clusters) and a simple random sample of the groups is selected.  Multi-stage sample – several levels of ran. sampling  Voluntary-response sample – researcher invites any member of population into survey  Convenience sample - sample selected but it’s easily accessible

23. In class / Home work: 1) Homework: Pg. 117 #1, 2, 3, 6, 8, and 9 *check your work with answers in the back – pg 618 2) Quiz on Friday – histogram/bar graph, definitions, sample types