Simple Random Sample
1: Get a list or “sampling frame”
- This is the hard part! It must not systematically exclude anyone.
- Remember the famous sampling mistake?
3: Select one person per random number
Systematic Random Sample
Select a random number, which will be known as k
Get a list of people, or observe a flow of people (e.g., pedestrians on a corner)
Select every kth person
Careful that there is no systematic rhythm to the flow or list of people.
If every 4th person on the list is, say, “rich” or “senior” or some other consistent pattern, avoid this method
Stratified Random Sample
Separate your population into groups or “strata”
Do either a simple random sample or systematic random sample from there
Note you must know easily what the “strata” are before attempting this
If your sampling frame is sorted by, say, school district, then you’re able to use this method
Multi-stage Cluster Sample
Get a list of “clusters,” e.g., branches of a company
Randomly sample clusters from that list
Have a list of, say, 10 branches
Randomly sample people within those branches
This method is complex and expensive!
The Convenience Sample
Find some people that are easy to find
The Snowball Sample
Find a few people that are relevant to your topic.
Ask them to refer you to more of them
The Quota Sample
Determine what the population looks like in terms of specific qualities.
Create “quotas” based on those qualities.
Select people for each quota.
The Theoretical Sample
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