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Linear Regression and Logistic Regression

Linear Regression

Linear regression uses the general linear equation  Y=b0+∑(biXi)+ϵ where  Y  is a continuous dependent variable and independent variables  Xi  are usually continuous (but can also be binary, e.g. when the linear model is used in a t-test) or other discrete domains.  ϵ ϵ is a term for the variance that is not explained by the model and is usually just called "error". Individual dependent values denoted by  Yj  can be solved by modifying the equation a little:  Yj=b0+∑(biXij)+ϵj

Linear Regression and Logistic Regression

Logistic Regression

Logistic regression is another generalized linear model (GLM) procedure using the same basic formula, but instead of the continuous  Y , it is regressing for the probability of a categorical outcome. In simplest form, this means that we're considering just one outcome variable and two states of that variable- either 0 or 1.

In other words,  Y  is a categorical variable,  Xi  are usually continuous

Linear Regression and Logistic Regression

The equation for the probability of  Y=1  looks like this:

P(Y=1)=11+e−(b0+∑(biXi))

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