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Week_14_dummy_variab - Dummy Variables Dummy variables are recoded nominal or ordinal variables Coded into dichotomous variables If original

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Dummy Variables Dummy variables are recoded nominal or ordinal variables Coded into dichotomous variables If original variables has k attributes, you create ( k –1) dummy variables 1 ScWk 242 Edward Cohen Week 14 Regression

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Why? Consider “ethnicity”—if coded 1=White, 2=AA, 3=Latino, etc., then regression sees this as a continuous variable, which is not accurate. It’s a categorical (nominal) variable. Why k 1? Because we don’t need to create dummy variables for all the original attributes. The analysis treats the missing dummy variable as a baseline with which to compare all others. (If you did code all attributes and tried to run the multivariate analysis, your analysis would be in error.) 2 ScWk 242 Edward Cohen Week 14 Regression
How it’s done Consider the variable “ethnicity” with five attributes: 1. White, 2. African American, 3. Latino, 4. Asian/Pacific Islander,

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This note was uploaded on 09/08/2010 for the course SCWK 242 at San Jose State University .

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Week_14_dummy_variab - Dummy Variables Dummy variables are recoded nominal or ordinal variables Coded into dichotomous variables If original

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