PSY 352 Chapter Notes - Chapter 2: Inter-Rater Reliability, Convergent Validity, Discriminant Validity
31 Aug 2016
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Measured by correlation coefficient (-1 to +1) correlation coefficient: (-1 to +1) direction of correlations: Positive: increase in one variable predicts increase in other: e. g. height and weight, e. g. health and income level. Negative: increase in one variable predicts decrease in other: e. g. self-esteem and depression. Larger (closer to +/- 1) = more predictive: small correlation: . 1 to . 3 (+/-, medium correlation: . 3 to . 5 (+/-, large correlation . 5 to 1. 0 (+/-) Remember, direction and size are independent: -. 65 is just as large a correlation as +. 65 strengths: Demonstrates covariation easy to do, low cost. When a variable cannot be manipulated weaknesses: Correlation does not imply causation (directionality problem) Third variable problem: experimental research experiment: measures causality (one variable influencing another) E. g. does sleep deprivation negatively affect your memory? independent variable (iv): variable manipulated by researcher to create groups ( conditions ) E. g. sleep deprivation vs. normal sleep dependent variable (dv): variable measured by researcher to compare conditions.
