NEUR 2001 Lecture 9: Lecture 9 Quasi-Experimental vs. Nonexperimental
20 Oct 2016
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Document Summary
Quasi-experimental vs nonexperimental: comparing differences in a pre-existing independent variable, comparing differences at different points in time, main difference depends on whether there are attempts to control threats to internal validity. Nonexperimental no control at all (just observe). Quasi-experimental some control; compare to another group that acts as the control. When the independent variable is a participant/subject variable or a time-related variable: participant variable age, weight, genetic etc, time-related variable pre/post event, event at different times. Effect of neuropeptide y on memory loss. Inability to randomly assign participants to groups poses problems for interpreting results. Even when all other variables are controlled, results can still be due to confounding variables (because of inherent differences in your starting sample). I. e. groups differ not just because of obesity; there may be life style factors, drug history, etc. Transgenic knock-out or knock-in mice to investigate the independent variable: transgene artificially constructed dna incorporated into genome. Knock-in gene inserted into genome for over-expression.
