# Tagged Questions

Refers generally to statistical procedures that utilize the logistic function, most commonly various forms of logistic regression

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### Caret package Varimp - feature selection question

I decided to use RFE using the caret package for feature selection for a logistic regression model. The documentation says the Varimp for linear model uses the absolute value of the t-statistic for ...
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### Interpretation of the regression coefficient of a proportion II

Following question: Interpretation of the regression coefficient of a proportion type independent variable In my model I have a log dependet variable. As indenpendet variables I have one proportion ...
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### Fit statistics and log-likelihood after multiple imputation estimation

I am working with four survey datasets, two of them without a certain variable which I impute using multiple imputation techniques. Afterwards, I use the complete data to estimate a set of logit ...
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### Categorical response variable prediction

I have the following kind of data (coded in R) ...
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### Large coefficients in logistic regression [duplicate]

This is from the book The statistical sleuth--A course in methods of Data analysis Chapter 20, Exercise 12(c)-(e). I am using logistic regression to predict carrier with possible predictors ...
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### Fitting a “sigmoid” function: Why is my fit so bad?

I tried to fit a curve to the black points using the following code. Why is the fit so bad? Do I need to fit another type of function? ...
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### Comparing the effect of a treatment that was optional for its receivers

In 2012 we collected data at our university about retention of students from first semester to second semester along with some other variables. The retention variable is binary, 'retained' or 'did not ...
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### Differences between Logistic Regression in Statistics and in Machine Learning

I just found out that Machine Learning also has logistic regression as one of its methods. Can someone please tell me the differences between logistic regression in Statistics and Machine Learning? ...
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### Effect of Wald-test and collinearity on Logistic Regression model selection

A researcher is interested in how variables, such as GRE (continuous), GPA (continuous) and rank of the undergraduate institution (categorical), affect admission into graduate school. The response ...
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### Logistic Regression: wald chi-square

I am running a logistic regression with a binary dependent variable and 5 class independent variables. One information the software I use returns, is the following: Effect / DF / Wald / Pr > ChiSq ...
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### May I validate a model after shrinkage?

I am doing a logistic regression using Frank Harrell's rms package. I went through the steps shown in his book and the rms ...
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### Correlated features produce strange weights in Logistic Regression

I have a data set with highly positively correlated features that I'm classifying with LR. AFAIK correlated weights are not a problem in the same way they are in Naive Bayes - overcounting will not ...
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### Estimating the effects of cumulative odds ratios - additive or exponential?

I have run some regression models that examine the effect of variable X (a 15 point continuous scale) on Y (a binary variable - not perform/perform a particular behaviour) using logistic regression. ...
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### How to deal with data having huge disparity in number in each class

I have data in which the number of negative cases in response is approximately 98% of the total sample size (total # records are approximately 1 million, Response is ...
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### Comparing different types of losses as functions of lambda?

The usual pictures we see when dealing with different loss functions look similar to this: Here we see y*f(x) on the x-axis with an error associated with it. Suppose I have a logistic regression ...
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### Aggregating or Pooling Multinomial Logistic Model Coefficients

I'm trying to recreate the MNL analysis like this paper or this one. In Excel I have a sheet with my choice column which contains the market share on each itinerary. Alternatively I also have the ...
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### Prediction with not significant covariate in logistic regression

I have a logistic regression model with several variables and one of those variables (called x3 in my example below) is not significant. However, x3 should remain in the model because it is ...
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### “Within transform” for logistic regression [duplicate]

I wish to model a binary outcome with controls for several thousand time fixed effects in a panel setting, without a special interest in the actual effect coefficient estimates. In variants of linear ...
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### What's the likelihood function in this case?

I have a data set with a binary response variable as non-zero survival cells (y=0) or zero survival cells (y=1), and I would like to build a model with explanatory variable X. I know that the most ...
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### Logistic Regression with time slices

I'm using logistic regression to predict student retention in an online course. I have a data of student interactions within a web platform of an online course. The course spans 6 weeks, with new ...
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### Propensity Score

What are the various methods used for binary classification other than logistic regression? What are the advantages of logistic reg. model in developing Propensity score w.r.t. other methods?? ...
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### Modeling time in multilevel logistic regression

I conducted an experiment in which participants listened to sentences while looking at pictures about the sentences on a computer screen. Whether at a given time point a participant looked at the left ...
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### Calculating the posterior probability

How do I calculate the posterior probability in R for individual observations and then classify the observation if the posterior probability is greater than 0.5? ...
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### How to interpret the significance of logistic regression variable? Something analogous to a partial F test in logistic regression

For ordinary linear regression with Gaussian noise, it is easy to interpret the significance of a variable. This is consistent with a partial F test. The square of the t-test for the second variable ...
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### Logistic regression, SPSS ignores my reference category and assumes another one

I am modelling logistic regressions in SPSS, the same model for different countries (well, with slight differences in the independent variables set due to collinearity diagnosis and stepwise results). ...
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### Logistic regression: maximizing true positives - false positives

I have a logistic regression model (fit via glmnet in R with elastic net regularization), and I would like to maximize the difference between true positives and false positives. In order to do this, ...
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### Modeling what should be a logistic regression but has no negative responses

I have a data set of reported food-borne illnesses and we're trying to determine what environmental conditions during food cultivation led to high bacterial counts in the food, and thus caused the ...
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### Logistic regression with categorical predictors, do log-odds differ from 0?

(My title is probably not very clear, but I don't know how to state it more clearly. So feel free to edit it. Thanks!) I have a 3 by 2 design, with a total of 6 conditions. The outcome is binary (0 ...
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