FRHD 3070 Lecture Notes - Lecture 9: External Validity, Internal Validity, Selection Bias
31 May 2018
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EXPERIMENTAL RESEARCH
• 3 things researchers do in experiments
o begin with hypothesis
o modify something in a situation
o compare outcomes with and without modification
• research questions for experimental research
o can manipulate conditions and intervene
o issues have narrow scale or scope
o issues focused on 1 or 2 variables
• random assignment
o why
▪ get two or more equivalent groups
o how
▪ begin with collection of subjects
▪ devise method to randomize that is purely mathematical
• ie flip a coin
▪ assign subjects with heads to one group
• experiment parts
o treatment/independent variable
o dependent variable
o pre-test
▪ measure of dependent variable prior to treatment
o post test
▪ measure of dependent variable after treatment
o experimental group
▪ group receiving treatment
o control group
▪ group not receiving treatment
o random assignment
• experiment design types
o classical
o pre-experimental
▪ one shot case study
▪ one group pretest post test study
▪ static group comparison
o quasi experimental and special designs
▪ two group post test only design
▪ interrupted time series
▪ equivalent time series
▪ latin square designs
▪ Solomon four group design
▪ Factorial designs
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