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Nonexperimental Research Methods

Nonexperimental Research Methods. Archival Research. Examine previously recorded data to answer a research question Public information Census data Court records Corporate reports Private information Credit histories Personal correspondence. Archival Research.

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Nonexperimental Research Methods

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  1. Nonexperimental Research Methods

  2. Archival Research • Examine previously recorded data to answer a research question • Public information • Census data • Court records • Corporate reports • Private information • Credit histories • Personal correspondence

  3. Archival Research • Sometimes the data are ready for analysis • Anderson (1989)—Temperature and aggression • Sometimes you need to work with it • Content analysis: Systematically examining qualitative information using predefined categories • Lau and Russell (1980)—Newspaper quotes

  4. Archival Research • Advantages? • Disadvantages?

  5. Meta-Analysis • Statistically combining results from multiple experiments • Uses effect sizes from individual studies as data points

  6. Case Studies • Intensive observation of one individual or a small group of individuals • Include a variety of data types • Luria (1968): The Mind of a Mnemonist • Advantages? • Disadvantages?

  7. Observational Research • Naturalistic observation • Observing behavior in the ‘real world’—people or animals in their everyday environments • Participant observation • Observer becomes part of the group being studied

  8. Potential problems • Absence of control • Participant reactivity • Unobtrusive measures • Observer bias • Operationally define behaviors • Use a behavior checklist • Have multiple observers

  9. Interobserver Reliability • When you use multiple observers, you need to assess how often they agree • Number of agreements divided by the number of opportunities to agree • Correlation between observers’ judgments

  10. Survey Research • Want to know about someone’s opinions, attitudes, behaviors? • Ask them! • Interviews • Phone surveys • E-mail or Internet • Written surveys • Social desirability

  11. Survey Research • Form of the questions is important! • Open-ended vs. closed • Yes/No Questions • Forced Alternative Questions • Multiple Choice Questions • Likert-type Scales

  12. Survey Research • Wording of questions is important! • Do you prefer your hamburgers flame-broiled or fried? • Do you prefer a hamburger cooked on a stainless-steel grill or cooked by passing the raw meat through an open gas flame?

  13. Who do you survey? • Most research in psychology is done with a convenience sample • Most research is concerned with relationships between variables • Most survey research—focused on describing attitudes, beliefs, behaviors of a group of people • Need to focus on how you sample participants

  14. Sampling • Population • Complete set of individuals or events • Sampling frame • List from which you draw your sample • Sample • Group that you obtain to represent the population

  15. Sampling • Random sample or Random selection • Every member of the population has an equal likelihood of being selected

  16. Sampling • Random sample with replacement • Chosen item or individual is returned to population, can be selected again • Random sample without replacement • Chosen item or individual is not returned to the population, can only be selected once • Stratified random sampling • Divide population into levels or subpopulations, random sample from them

  17. Nonrandom sampling • Heterogeneity sampling • Sampling for diversity or variety • Modal instance sampling • Sampling for the most typical case • Expert sampling • Sample of people with known experience or expertise in some area • Quota sampling • Sample until you have a specific number from each subgroup in a population • Snowball sampling • Sample a few who fit your criteria, ask them to identify others who would also fit

  18. Survey participants provide you with one or more responses • You use a statistic to summarize the responses from a group of people • If you could measure the whole population, you’d have a population parameter

  19. The Sampling Distribution • Imagine drawing three samples from the same population—collecting the mean • Means would differ slightly, but they should be pretty similar • Imagine now drawing an infinite number of samples from the same population and computing an average from each one • Those averages should be normally distributed

  20. The Sampling Distribution • Average of the sampling distribution should be the population parameter • Standard deviation of the sampling distribution tells us how the samples would be distributed: this is known as the standard error

  21. The Sampling Distribution • Standard deviation • Spread of scores around the average in a single sample • Standard error • Spread of averages around the average of averages in a sampling distribution

  22. The Sampling Distribution • Standard error is calculated from the standard deviation in your sample • Also related to sample size • Remember the 65%, 95%, 99% rule from a normal distribution?

  23. The Sampling Distribution

  24. The Sampling Distribution • So, using your sample, you can estimate the average for the population and give odds that the actual population mean falls within a certain range with the confidence intervals

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