STAB22H3 Chapter Notes - Chapter 13: Statistical Unit, Random Assignment, Dependent And Independent Variables
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STAB22H3 Full Course Notes
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Studies where researchers don"t assign choices, they simply observe them. Retrospective study subjects are identified first and then data is collected on an aspect of their past, can have errors because they are based on historical data. Used widely in public health and marketing, used for discovering trends and possible relationships. Prospective study identifying subjects in advance and collecting data as events unfold. An experiment requires a random assignment of subjects to treatments. An experiments studies the relationship between two or more variables at least one explanatory variable (a factor) that is manipulated, and at least one response variable to measure. The experimenter actively and deliberately manipulates the factors to control the details of the possible treatments and assigns subjects to those treatments at random. Experimental units individuals on whom we experiment, human units are called subjects or participants. Levels of a factor specific values of a factor that the experimenter chooses.
