Monthly Archives: July 2013

Understanding Logistic Regression Coefficient Output:
Part 4 — Making Predictions

This article discusses making predictions using logistic regression. It is part 4 of a five-part series focused on understanding and interpreting the logistic regression coefficient output table. Click here to see a brief summary of the focus of each of … Continue reading
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How to Solve the Logistic Regression Equation for the Probability p.

As discussed previously, in logistic regression the log odds is modeled as a linear function of the -variables. That is     To solve this equation for , we first apply the exponential function to both sides of the equation: … Continue reading

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Logistic Regression Odds Ratio — The Math

In this article, I am going to show you why the odds ratio for an -variable in a logistic regression is simply the exponential of the regression coefficient. This article just contains “the math” and no interpretation. A discussion of … Continue reading

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Understanding Logistic Regression Output:
Part 3 — Assessing the Effects of the X-Variables

In logistic regression, as in least-squares regression, you often want to try to assess the effects of the independent -variables on the dependent -variable. In logistic regression, however, things are somewhat more complicated than in least-squares regression as I explain … Continue reading
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What is the Odds Ratio in Logistic Regression?

Most logistic regression software outputs (or can be asked to output) odds ratios along with the regression coefficients. These odds ratios are the exponential of the corresponding regression coefficient:     For example, if the logistic regression coefficient is the … Continue reading

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Understanding Logistic Regression Output:
Part 2 — Which Variables Matter

This article discusses one of the most important uses of the coefficient table, determining which variables matter. It is the second part of a five-part series discussing the logistic regression output coefficient table and its uses. Click here to see … Continue reading
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What is the (Multivariate) Logistic Regression Equation?

In logistic regression, the log odds is modeled as a linear functions of the -variables. Thus, the logistic regression equation is:     Once the logistic regression has been “run,” the software will calculate estimates for , , , … … Continue reading

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Understanding Logistic Regression Output:
Part 1 — The Coefficient Table

As with least-squares linear regression, the most important part of the output of a logistic regression is the regression coefficient table. In this five-part series of articles, which parallels and references the five-part series reviewing the least-squares regression coefficient table, … Continue reading

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What is Ordinal Logistic Regression?

Ordinal Logistic Regression is logistic regression using an ordinal variable. An ordinal variable is a categorical variable where order matters. A variable that takes on the values of “very bad,” “bad,” “mediocre,” “good,” “very good” would be an example. The … Continue reading

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What is Nominal Logistic Regression?

Nominal Logistic Regression is logistic regression using a nominal variable as the dependent Y variable. The “nom” in “nominal’ comes from the Latin for “name” (not “number”) like in the word “nomenclature.” So a nominal variable is a variable whose … Continue reading

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