2.3 Sampling Techniques Terms Population: refers to all individuals who belong to a group being...
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Transcript of 2.3 Sampling Techniques Terms Population: refers to all individuals who belong to a group being...
2.3 Sampling TechniquesTerms
Population: refers to all individuals who belong to a group being studied
2.3 Sampling TechniquesTerms
Population: refers to all individuals who belong to a group being studied
Sample: a group or items selected from the population
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?
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
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.
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
More terms Sampling frame: the group actually
have a chance of being selected
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
More terms Systematic sample: a sample selected
by listing a population sequentially and choosing members at regular intervals
interval = population size / sample size
Systematic sample example
interval = pop. of 100/ sample of 20 = every 5th person surveyed
Stratified sample: a sample in which each group is represented in the same proportion as it appears in the population
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.
Method Stratified sample:
So you choose to survey a fraction of each group within the sample to ensure each group is represented.
Method Stratified sample:
Choose a fraction with justification, say 30%.
Grade# of
StudentsRel.
FrequencyNumber
Surveyed8 12 0.059 32 0.1310 47 0.1911 69 0.2912 78 0.33Total 238 1
More terms Stratified sample:
Choose a fraction with justification, say 30%.
Grade# of
StudentsRel.
FrequencyNumber
Surveyed8 12 0.05 3
9 32 0.13 9
10 47 0.19 14
11 69 0.29 20
12 78 0.33 23
Total 238 1 69
More Sample Types
Cluster sample - the total population is divided into groups (or clusters) and a simple random sample of the groups is selected.
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
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
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.
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
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
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