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Module 3

Module 3. Research Strategies: How Psychologists Ask and Answer Questions. Can a 4 year old keep themselves from eating a marshmallow now, If they are told they will get two later?. Video. Y Psychology: Scientific Study of Behavior and Mental Processes. Goals.

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Module 3

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  1. Module 3 Research Strategies: How Psychologists Ask and Answer Questions

  2. Can a 4 year old keep themselves from eating a marshmallow now, If they are told they will get two later? Video

  3. Y Psychology: Scientific Study of Behavior and Mental Processes Goals • Describe Behavior • Predict Behavior • Explain Behavior • Control Behavior

  4. Psychologists must be skeptical and think critically What is the evidence? How was it collected? Psychology is Empirical Knowledge acquired through observation

  5. Like all verdicts, the value and validity of the evidence must to examined.

  6. Proof Studies provide EVIDENCE to support or refute a theory. Studies NEVER provide PROOF. Like all verdicts, the value and validity of the evidence must to examined.

  7. General Principles (Theory) Empirical Predictions Evidence Hypothesis Observations (data) Advantage: Self correcting cycle.

  8. Develop theory Caffeine improves people’s study skills Form hypothesis Students who drink 2 or more caffeine beverages per day have higher GPAs Test hypothesis Record amount of caffeine consumed and GPA for each student in the study. Refine theory Do the data support the theory? Revise the theory to better fit the data. Scientific Method in Psychology

  9. General Questions to Ask About a Study 1. Identify the variables! Variable: Anything that takes on different values, at different times, places, or in different individuals. All studies have variables. They are the constructs (qualities) we measure (e.g., intelligence, personality, or reaction times).

  10. You need to ask how the variables are defined? Is the measure Valid? (Does it measure what it claims to? Is the measure meaningful? Useful?) Operational Definitions - Detailed descriptions of measurement criterion.

  11. How was ability to delay gratification (self control, self discipline) operationally defined in the Marshmallow Study?

  12. 2. Is the measuring device reliable? - will the same value be obtained - by different researcher - at different times

  13. Statements of precise operational definitions allow scientists to Replicate studies. Replications allow us to determine if the results of a study are reliable.

  14. Concept Check 1.What variable/construct measured in this study? 2. How is this variable operationally defined? 3. Is this a valid way of measuring this construct? 4. Is it a reliable way of measuring the construct? 5. Do the results support the conclusions made by the researcher?

  15. Population Sample 2. You need to ask who is in the study? Sample Collection of Ss used in a study Population Larger collection of people about which we want to generalize Sampling Bias When the sample is not representative of the larger population

  16. If sample is restricted or biased this limits the generalizability. Volunteers? Convenience Samples (University Students)?

  17. Small numbers of subjects can be used to estimate the behavior of a larger group as long as the sample is not biased. Representative Samples - matched demographics. Random Samples - eliminates bias.

  18. Replications to Test Generalizability to other Populations and Times Often studies are done of specific populations and researchers may want to know if you would get similar results with other populations. So they replicate the study with samples from other populations. e.g., Marshmallow Study was replicated with Children in Columbia. Would we get same results if we replicated the study today?

  19. Types of Research 1) Descriptive: No Hypothesis 2) Relational Studies: (Circumstantial Evidence) 3) Experiments - evidence of cause and effect. Remember: None of these are Proof.

  20. Descriptive Studies • Case Studies Detailed description of one person’s behavior Useful for Rare Cases (e.g., Serial Killers, or Rare Disorders). • Concerns • Experimental Bias • Subject Bias • Generalizability

  21. 2) Naturalistic Observation Studies - real world settings Concerns • - defining variables • - sampling (who, where and when) • - Experimenter Bias • - Observation can change behavior

  22. 3) Surveys Ask People about behaviors or attitudes Main Advantage: Can survey large numbers. Concerns • Biased Samples 4 out of 5 dentists recommend brand X. • Generalizability • Subject Bias • Wording and method effects results

  23. Class Survey. Reasons for taking Class Cards All Top 2 5 Hour Energy Video

  24. Relational Studies: what variables tend to go together in predictable ways. Correlations Two variables measured on same person. Correlation statistic ( r ). Ranges from -1 to +1

  25. Positive - change in same direction. High on one variable predicts high on the other. Negative - change in opposite directions Low on one variable predicts high on the other.

  26. Absolute Value of r. Strength of the relationship. r = +1 or r = -1 perfect prediction. r = 0 no ability to predict. The closer to +1 or -1 the stronger the relationship The closer to 0 the weaker the relationship

  27. * * * * * * * * (-) r * * * * * * * Age * * * * * * * r - statistical relationship twixt 2 variables (age & penalties) * * Penalty Minutes Correlations Do young hockey players take more penalties than old hockey players?

  28. Concept Check Predict the correlation between these variables (High, Medium or Low? Negative or Positive) Weight and Height IQ and shoe size SAT scores and Grades in College Miles you have drive since a fill-up and amount of gas in your tank. Number of Storks and Birthrate in a town

  29. Correlation Causation Several Interpretations A could cause B B could cause A C could be causing both A and B Warning: People often try to use correlations as evidence of cause. This is wrong.

  30. True Experiments Independent Variable (IV) - Variable that is manipulated by Researcher. (Cause) Dependent Variable (DV)- Measure of the effect of manipulating the IV • Purpose:To see if changes in the IV cause changes in the DV.

  31. True Experiments • objective measure • a difference is produced (manipulated) • all other variables held constant

  32. If these three requirements are met, what can we conclude about our results? Cause Effect Light Growth

  33. When we conduct Experiments with People we have an Experimental Group and a Control Group. The two groups are treated exactly the same except for the IV. The level of the IV is under the control of the experimenter (I.e., any person in the study could be assigned to either the experimental or the control group.)

  34. Some studies compare different groups of people to each other. Random Assignment ensures that there is no systematic reason why the two groups should differ. Any differences are due to chance.

  35. Confound– anything other than the manipulated variable that is different between two conditions. Serves as an alternative explanation of the cause of differences between conditions.

  36. Natural Experiments - look like experiments, but they are confounded. • Variable is not manipulated by experimenter. • e.g., comparisons of pre-existing or self-selecting groups. • Males vs. Females • People who use Match.com vs. those who do not.

  37. If Males score better on Math tests than Females can I say being Malecauses better math scores? Other explanations?

  38. Other Biases (Can occur in any type of study) Experimenter Bias - blind Observers Expectancy Effects - e.g., placebo effect Double blind procedures. - both observer and subjects are blind to expected results.

  39. Statistics - allow us to describe findings Measures of Central Tendency Mean – arithmetic average Medium – Midpoint Mode – Most Frequent

  40. Measures of Variation How much variation is there is the measures? Range – lowest through highest. Standard Deviation – Average distance of the scores from the Mean. Larger the Standard Deviation the more variable the scores in the distribution are.

  41. Shape of Distributions Symmetrical - scores evenly distributed around the mid-point of the distribution. Skewed Distributions- scores pile up on one end of the curve. IE(DS)

  42. In a symmetrical, unimodal, distribution the Mode, Median and Mean will all be the same. When the distribution is skewed, or contains some deviant scores, these three measures can be very different. IE(DS)

  43. IE(DS)

  44. Normal Curve Bell shaped curve describes many variables in the natural world. Allows us to estimate the probability of scores at any place in the distribution.

  45. Tests of Statistical Significance If a result is statistically significant, the difference between conditions is unlikely to be due to chance alone. Statistical Significant  Important Better question: How big is the difference?

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