# Tagged Questions

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

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### Treating categorical variables in logistic regression in SAS

I am scoring my dataset using a logistic model. For getting the betas (coefficients) I used proc logistic y = x1 x2 x3. To tell the model which are class variables ...
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### Categorical response variable prediction

I have the following kind of data (coded in R) ...
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### how to interpret the result of significant regression of binary logistic yet all predictor is insignificant [duplicate]

I am performing research on Product attributes of mineral water toward purchase decision. However, the result of -2log likelihood test showed that my model is fit enough yet my result of Hosmer and ...
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### Accuracy outcomes puzzle when using logit for prediction

I'm building a predictive logit model for a rare event using 5-fold cross-validation. I have three years of data. I build a model with a training set of years 1 and 2, then I test on the test set with ...
55 views

### How to do mixed logistic regression with multiple repeated measures in R?

I have data from a psychology experiment in which participants were assigned to one of 3 training conditions and then gave responses for 16 trials for each combination of two within-subjects factors, ...
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### Multinomial Logisitic Regression in Mlogit For Dummies - Building a Model and Extracting its Coefficients

I am trying to do a multinomial logistic regression on some data that I generated. I am using R and the package mlogit. My data looks like the following: ...
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### Prediction using multinomial logit regression in R

I've got three variables, a factored (c) and two ordinal independent (a,b). Every variable has five categories (1,2,3,4,5). Thus, I fitted a multinomial logit regression (testus, see below) with the ...
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### PDF of sum of one continuous logistic and one Bernoulli random variables

I need some help people. I have a logistic r.v. $V\sim \Lambda (0, \frac {\pi^2}{3})$ and a Bernoulli $Z \sim B(p_z)$, independent. I have also $c\in R$, $\tilde Z = cZ$, and I have to find the ...
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### Low intraclass correlation although between variance is very high in random effects model

I don't understand why a random effects model can give you a very low rho (intraclass correlation coefficient), if the between variance (between subjects) in your ...
80 views

### Can the EM algorithm be applied to my problem? Input data set is based on a function of parameter

I understand EM algorithm is often used for missing data/mixture problem. But can it be used to optimize a particular type of likelihood based on jointly fitting variables and transformations of those ...
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### Hierarchical Multiple Regression vs Ordinal (logistics) regression

This is my first research assignment and I feel overwhelmed and confused. I have been informed by my supervisor to do a hierarchical multiple regression using SPSS. I noticed that my dependent ...
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### Account for both between and within variance in panel data

I have a general question on fixed-effects and mixed-effects models for panel data. I am doing a logistic regression on panel data, with data measured on the individual level. I understand that by ...
80 views

### Machine Learning to Predict Class Probabilities

I am looking for classifiers that output probabilties that examples belong to one of two classes. I know of logistic regression and naive Bayes, but can you tell me of others that work in a similar ...
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### How to validate and compare models predicting a binary variable?

I have a question about determining which models are "better" and how to assess that info. Let's say I have three models, each which predicts our bid on won ping. Our bid is a continuous variable and ...
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### How to handle categorical dependent variable using logistic regression when one of the categories never occurs in the sample

I have a multinomial logistic regression model. One of the output categories is not observed in the data set that I'm using. Example: 4 different diagnoses (response variable) in the population, ...
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### Logistic regression shows linear margins for different levels of independent variables

Having read about logistic regression, I understand that the probabilities of the success of the DV, P(Y=1), do not necessarily grow the same at every level of the ...
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### glmnet converges extremely slowly for multinomial with mass function concentrated at one point

If I have a response vector that is mostly one class label, convergence of Lasso in glmnet will be extremely slow, for example: ...
726 views

### What does the logit value actually mean?

I have a logit model that comes up with a number between 0 and 1 for many cases, but how can we interprete this? Lets take a case with a logit of 0.20 Can we assert that there is 20% probability ...
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### How to find cutoff values in multinomial regression?

Updated I have a data set with five continuous variables measuring an index in a population. For finding underlying classifications in the population based on the five observed variables, I did a ...
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### Estimation parameters using Generalized Method of Moments and Generalized Empirical Likelihood with R

I have two density functions: $h_{1}(x)$, $h_{2}(x)$. I want to estimate parameters from one dataset using $h_{1}$ and $h_{2}$ andthe GMM estimator or the GEL : from the article "Computing ...
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### Correcting for heteroskedasticity in Logit fixed-effects model

I found out that my panel data 'suffers' from heteroscedasticity by doing the test described on Stata FAQ, Testing for panel-level heteroskedasticity and autocorrelation. I understand that the $H_0$ ...
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### How can I increase the accuracy of predicting the occurrence of event using logistic regression?

I will work on climate data to predict if a disease it will happen or not on a crop. During search I found logistic regression is best choice for my research, but it has several problems led to reduce ...
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### Twitter user data - Fixed Effects Logit the right/only choice?

I'm wondering whether a fixed-effects (logit) model fits the purpose of my study, and would like to get some feedback or ideas which other models could potentially be useful: I have an unbalanced ...
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### Probabilities from Logistic Regression

I have built a logistic regression model in R and though the result appears to be satisfactory to some degree, there is one question I have not be able to address. I am not sure if my approach is at ...
25 views

### Regarding importance of variables after applying PCA

I have a data with 15 variables. I did PCA on it to come up with 3 factors all of which had 5 variables each that explained the corresponding variance in those factors. After completing the entire ...
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### Logistic Regression and how to judge model fit and parameter influence

I want to show statistical significant impact of about 15 different independent variable on a binary dependent variable (I am not a statistician). Some of my independent variables are term counts in ...
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### Frequency weights for logistic regression in R

I would like to fit a logistic regression model in R. The data collection process results in an un-balanced amount of events and non-events. I could re-sample from the data to re-create the original ...
52 views

### Aggregating predicted probabilities from a classifier

I have an existing logistic regression used to forecast whether a given action will take place or not. The unit of analysis is the individual person. For the sake of the question, assume a default ...
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### Should predictive buying models change when products/prices change?

My company creates logistic regression models that predict who will buy based on 1st & 3rd party online click data. We use this to target online visitors with interventions like retargeting ads. ...
442 views

### Binomial GLM and different sample sizes

I have a data set which consists of binomial proportions, let's say the success rate of converting a customer depending on the advertisement, the customer age, and various other factors. For some ...
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### Handling Infrequently Occurring Categorical Variables

I'm dealing with some data where there are some infrequently occuring categorical variables related to a binary prediction target. For example marketing partners... some send 1000s of leads but many ...
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### Decision criteria for logit and regression analysis

When we use either logit or linear regression, will be the deciding factors same (P, F, R sq, and R adj)?
20k views

### What is the difference between linear regression and logistic regression?

What is the difference between linear regression and logistic regression? When would you use each?
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### Performing binary logistic regression with equal number of cases and non-cases

The best way to ask my question is to present an example scenario: Let's say that the outcome of interest is lung cancer (1 = lung cancer; 0 = no lung cancer) and a researcher has 200k records (where ...
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### Different results by using chi square test and logistic regression

I am working on a problem to identify the risk factors to infection after operation. So there are risk factors such as age, pre existing condition, cause of infection etc. Since the dependent variable ...
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### Logistic regression - the model is significant in predicting the DV, yet the percent correct decreases [closed]

How can this be? My thoughts are that while the percent correct decreased from 80.8% to 80% with the model, perhaps the model is regarded to be a significant predictor due to the specificity having ...
46 views

### 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 ...
174 views

### 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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### 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 ...
3k views

### How to deal with perfect separation in logistic regression?

If you have a variable which perfectly separates zeroes and ones in target variable, R will yield the following "perfect or quasi perfect separation" warning message: ...
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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? ...
386 views

### How to deal with quasi-complete separation in a logistic GLMM?

Update: Since I now know that my problem is called quasi-complete separation I updated the question to reflect this (thanks to Aaron). I have a dataset from an experiment in which 29 human ...
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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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### How to conduct a multilevel (hierarchical) binary logistic regression (in SPSS, R, or other software)?

I have a model with occurrence of a disease represented by a binary dependent variable (DV) and 8 independent variables (IVs) at different levels. I need to create a multi-level model, in which the ...
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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 ...