Psychology 2800E Lecture Notes - Lecture 16: Observational Error, Suger, Random Assignment
27 Sep 2016
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1 establishing equivalence between conditions so we have a standard of comparison to assess the effects of the iv (treatment) Simplest case: two conditions: 1 receives treatment and other gets no treatment ( control) Must be equivalent ( except for getting the treatment or not) then, compare the two conditions. Part 1: establishing equivalence ( for standard of comparison ) We need control condition eg we can have a pretest ( provides baseline with no treatment) introduce treatment posttest (assess effects of treatment) Compare pretest to posttest but there are many threats to internal validity ( see jan 14) Sources of uncontrolled variability ( next 2 lectures) E biases f other confounds ( no lecture) see w and m ch 6 p153-155. The carrot experiment ( vitamin a and nigh vision) Night blindness: inability to see low levels of light ( don"t see well in the dark)
