NEUR 2001 Lecture Notes - Lecture 7: Dependent And Independent Variables, Confounding, Repeated Measures Design
20 Oct 2016
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Simplest form changing one variable causes change in second variable. Four basic elements: manipulation, measurement, comparison, control. Two critical components: independent vs dependent variable, experimental vs control group. Does eating chocolate cause obesity or obesity cause you to eat: feeding and arcuate neuronal activity. Arcuate is a part of the hypothalamus. Use optigenetics to turn light sensitive protein channels on and off, controlling these neurons. What you observe cannot be influence by other variables: eliminate confounding variables. Confounding variables change with the independent variable. Obscuring variable becomes confounding if it influences the dependent variable: control obscuring variables. Easy for some conditions but not for others. Light, temperature, noise, time cannula placement: matching and randomization, keep in mind the balance between external and internal validity. Holding variables constant and matching may limit generality. Independent variable: this is what you manipulate, cause of your effect, at least 2 levels. Diet chow, high fat diet: usually only one.
