Sampling Methods in Qualitative and Quantitative Research

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  • + samirayar samir ayar 1 month ago
    a very effective slides . can I have a copy of it to sent to : samirayar@yahoo.com
  • + guest1de9c51 guest1de9c51 7 months ago
    Thank you for making this ppt. I am studying The Logic of Sampling right now in grad. school and the book is so confusing. This ppt makes it all come together
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Sampling Methods in Qualitative and Quantitative Research - Presentation Transcript

  1. Sampling in Qualitative and Quantitative Research
    A practical how-to
  2. Key themes
    A famous sampling mistake
    Quantitative assumptions in sampling
    Qualitative assumptions in sampling
    Types of sampling
    Ethnographic sampling
    Interview sampling
    Content analysis sampling
    How many?
  3. A famous sampling mistake
  4. A famous sampling mistake
    That’s Truman
    They only asked rich, white people with telephones who’d they vote for. Sadly, they published their mistake
  5. Even with proper sampling…beware!
    “…predicting behavior on the basis of knowledge of attitude is a very hazardous venture.” Meaning, predicting social behavior is often misguided. Keep that in mind!
  6. What exactly IS a “sample”?
  7. What exactly IS a “sample”?
    A subset of the population, selected by either “probability” or “non-probability” methods. If you have a “probability sample” you simply know the likelihood of any member of the population being included (not necessarily that it is “random.”
  8. What do quant researchers worry about?
    I really spend a lot of time wondering how to measure things.
    I want to make sure others can repeat my findings.
    I want to know what causes something else.
    I wonder how small patterns generalize to big patterns.
  9. Assumptions of quantitative sampling
    We want to generalize to the population.
    Random events are predictable.
    We can compare random events to our results.
    Therefore…
    Probability sampling is the best approach.
  10. What do qual researchers worry about?
    I really want my research approach to be flexible and able to change.
    I want to describe the context in a lot of detail.
    I want to see the world through the eyes of my respondents.
    I want to show how social change occurs. I’m interested in how things come to be.
  11. Assumptions of qualitative sampling
    Social actors are not predictable like objects.
    Randomized events are irrelevant to social life.
    Probability sampling is expensive and inefficient.
    Therefore…
    Non-probability sampling is the best approach.
  12. Types of samples
  13. Simple Random Sample
    Get a list or “sampling frame”
    This is the hard part! It must not systematically exclude anyone.
    Remember the famous sampling mistake?
    Generate random numbers
    Select one person per random number
  14. 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 kthperson
    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
  15. 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
  16. 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!
  17. The Convenience Sample
    Find some people that are easy to find
  18. The Snowball Sample
    Find a few people that are relevant to your topic.
    Ask them to refer you to more of them.
  19. 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.
  20. The Theoretical Sample
  21. What about generalizing?
    “Our findings have a margin of error of + or - 4%, 19 times out of 20.”
    “The average man is 35% more likely to choose this option over the average woman.”
  22. Proviso in non-probability sampling: no generalizing
    “Our findings have a margin of error of + or - 4%, 19 times out of 20.”
    “The average man is 35% more likely to choose this option over the average woman.”
  23. Ethnographers sample…
    People
    Places
    Contexts
    Times
    Events
  24. Interviewers sample…
    People
    Places
    Times
  25. Content analysts sample…
    Media
    Dates
  26. How many?
    Qualitative researchers seek “saturation”
    “How many” isn’t the issue. Do you understand the phenomenon? Have you learned enough?
    Mere numbers are irrelevant. You want “verstehn” or deep understanding
    Quantitative researchers seek statistical validity
    Can you safely generalize to the population? Have you systematically excluded anyone? (See the “famous sampling mistake”!)
  27. Improving Response Rates
    Personalize the invitation
    Offer money -- no strings attached!
  28. Copernicus ConsultingDesign research and strategy
    http://www.copernicusconsulting.net

+ Sam LadnerSam Ladner, 2 years ago

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