PSY BEH 11A Lecture Notes - Lecture 4: Twin Study, Random Assignment, Internal Validity
17 Oct 2016
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Document Summary
Independent variable is controlled and manipulated, dependent variable is measures. Correlation studies: causality cant be inferred form simple correlation studies. Nonlinear relationships: number of pounds bench-pressed based on age. Low ambitions lead to poverty and vice versa: not enough information to determine causality. There may be multiple factors that can contribute to one thing: correlation does not mean causation. The correlation coef cient is an index which quanti es the relationship between two measured (dependent) variables. Perfect relationships are almost never observed: r=0 means no linear relationship between the two things. True experiments: manipulation of independent variable, comparison of dependent variable, control of all other variables. Includes control, manipulation and comparison: within subject design. Sample of subjects-independent variable a-measure dependent variable-independent variable b-measure dependent variable- compare result of the measurements of the dependent variables: cant be used when effects are irreversible. This way is more sensitive to small effects but is also more ef cient.
