Experimenter bias two sources of experimenter bias

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Experimenter bias Two sources of experimenter bias Expectancy effects:When an experimenter expects certain types of behavior from participants Treating different groups differently:depending on the condition to which they were assigned Experimenter bias affects internal and external validity Steps to reduce experimenter bias blind technique the experimenter does not know the condition to which a participant has been assigneddouble-blind technique neither the experimenter nor participant knows the condition to which a participant has been assigned e.g. placebo vs. active drug Automate the experiment
2019/1/31 9 Confounds & Artifacts
2019/1/31 10 Confounding Variables Extraneous Variable (s) Influence the Dependent Variable Happen to vary systematically with dependent variable Often called the 3rdvariable problem Could be anything related to your dependent variable: Age, SES, Hair Color, Home Town To avoid this experimenters can 1. Hold relevant extraneous variables constant 2. Match Values in both groups 3. Randomization 19 Confounds & Artifacts (cont’d.)Confounds threaten internal validity Artifacts threaten external validity

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