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# Questions tagged [logistic]

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

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### Logistic regression discrimination threshold with cross validation [duplicate]

I'm using logistic regression to perform binary classification with training, CV, and test sets. When is the most appropriate time to pick a discrimination threshold to balance positive and negative ...
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1 vote
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### Logistic Regression Algorithm? [closed]

I am studying on some Machine Learning concepts. I am looking for logistic regression(multiclass) and logistic regression classifier and I should learn how to change it to penalize large weights. I ...
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### Logistic vs linear regression

Let's say I run a linear regression model with a binary dependent variable. If I ran logistic regression on the same data would the results be comparable or exactly similar? By results I mean both the ...
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### How do important and insignificant variables impact model?

I am working to build a model using logistic regression. There is one variable which has strong predictive power. But based on business rule, I cannot include this variable in the model. On the other ...
1k views

### How to describe characteristics of the curve fit by a four parameter non-linear regression?

I've fit a non-linear mixed effects model with a four parameter logistic function. My specific interest is in characterizing the point on the curve at which the horizontal component of the curve meets ...
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### R: mlogit error on data - "system is exactly singular"

So I have data from a randomized blind trial of 1mg of nicotine gum on dual n-back working memory scores; I analyzed them as usual with a t-test and found a small increase in means but a large ...
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### Experimental Design for Comparative Responses

Suppose I were looking to optimize the amount of certain spices in a chili spice recipe. The textbook experimental design would have me encode the amount of each spice in the design variable, choose ...
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### Logistic regression with low event rate

I'm trying to build a logistic regression model to predict 90+ Days past due(DPD) events. The size of the database is 96000, with an event rate of 6%. We ran the entire data set through the info value ...
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### Kernel logistic regression vs SVM

As is known to all, SVM can use kernel method to project data points in higher spaces so that points can be separated by a linear space. But we can also use logistic regression to choose this ...
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### Aliases in fractional factorial designs

I am looking at using a fractional factorial design in order to reduce the number of treatment runs for an experiment involving a binary outcome. The idea is to create the design, then, since this is ...
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### Regression Analysis model [closed]

Objective is to predict a car's retail value based on the characteristics of mileage, make, model, engine size, interior style, and cruise control. Price The price of the vehicle Cylinder 4,6,8 ...
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### Reference category in multinominal logistic regression

I was wondering how you get beta values for the final model if you don't have a reference condition? I am running a multinominal logistic regression using a dependent variable that has 6 levels - ...
207 views

### How to code values for males when they're only meaningful for females? [duplicate]

I'm building a predictive model for a medical condition that happens in both men and women. Physicians have reported that in some cases for women, their menstrual history seems to be a risk factor, ...
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### Logistic regression-like model for non-discrete outcomes

If I have a set of continuous predictors $X$ and a binary outcome $Y$ and I wanted to build a predictive model of $P(Y|X)$, I would start with a logistic regression model. However, in my particular ...
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### Checking the regression model's performance

I am R-tool beginner. I have a question regarding how to know the performance of a linear regression model by using validation data. My approach was Create training and validation data sets from ...
61k views

### What is the difference between logistic regression and neural networks?

How do we explain the difference between logistic regression and neural network to an audience that have no background in statistics?
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### Extending logistic regression for outcomes in the range between 0 and 1

I have a regression problem where the outcomes are not strictly 0, 1 but rather in the range of all real numbers from 0 to 1 included $Y = [ 0, 0.12, 0.31, ..., 1 ]$. This problem has already been ...
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### probability of interest [closed]

The model that I created in R is: fit <- lm(hired ~ educ + exper + sex, data=data) what I am unsure of is how to fit to model to predict probability of interest where p = pr(hiring = 1). Edit:...
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### What type of regression model do I use?

$y = \mathbf{X} \beta$ + $\epsilon$ + $m$ Where y, $\epsilon$, and $m$ are $n \times 1$ column vectors, $\beta$ is $p \times 1$ and $\mathbf{X}$ is $n \times p$. $y$ is a noisy time-series signal ...
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### Interactions make terms significant in regression when they should not be

I am writing code to prepare for running a logistic regression on real data. I have sample data for all my IVs but not for the outcome variable. There are many strong dependencies among the IVs but I ...
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### Algorithm convergence with logistic classifier

I am doing a college classification project, in which I am required to classify some handwritten digits. Assume that my input is a N*D where D is the number of features in each input sample and I need ...
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### Confidence interval for proportions

I have some data like this: id pop var 1 593 51 2 592 31 3 346 20 4 1214 70 5 1063 66 6 1370 71 each ...
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### Logistic Regression model keeps kicking out 1 dummy

I have a dataset in which each row belongs to one of 8 categories. I'm running a logistic regrssion on it using R. I created dummy variables for each of these categories. In my logistic regression ...
157 views

### logistic regression always yielding increasing f'n when should sometimes be decreasing (using R)

I'm modeling a set of outcome data the depends on two parameters: time, T -100 < A < 100 I've done logistic regression using R with the command: ...
552 views

### Sensible to include ratio as a variable in logistic regression?

I'm creating a generalised linear regression using a binomial link function for two variables A and B. From looking at the data it appears that A/B may have discriminatory effect. Is it sensible to ...
1k views

### Logistic regression: big difference in predicted values and highly significant, but poor goodness of fit

I have a logistic regression model with a dichotomous response variable and predictors coded from $1$ to $10$ and from $0$ to $18$. When I fit the model, I get these results: ...
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### poisson vs logistic regression

I have a cohort of patients with different length of follow-up. So far I´m disregarding the time aspect and just need to model a binary outcome-disease/no disease. I usually do logistic regression in ...
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### Whether to use linear regression or not

Effects of growth hormone (GH) replacement with recombinant human GH on bone and mineral metabolism were studied in 36 GH-deficient children. Several outcomes, including serum ionized calcium levels, ...
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### When the response variable is a proportion (r/n) in proc logistic, how to express the model in terms of $\pi, \alpha, \beta$?

A (SAS documentation file) (page 1906) on "The LOGISTIC Procedure" gives the following procedure- proc logistic; model r/n=x1 x2; run; Here, n represents the ...
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### Adding not chosen alternatives as data to logistic regression model

I am interested in predicting shopping behaviour in a shopping center. I have a database with the chosen alternatives (shop) and variables describing that alternative (like type and size) and the ...
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### Choosing between logistic regression and Mann Whitney/t-tests

I have a dichotomous variable $A$, which does not have an a priori determined proportion of 0's and 1's, and a continuous variable $b$. In scenario 1, I decide to designate $A$ as the independent ...
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### Shifted intercepts in logistic regression

I have a question about the effects of shifting the intercept in a logistic fit on the mean of a particular transformation of the scores. Here is the notation I will be using for the question. The ...
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### "Wrong Sign" On Regression Coefficients - Hierarchical Multiple Linear Regression

I am analyzing my data on the relationship between spirituality and negative emotional states (depression, anxiety, and stress) using a hierarchical multiple linear regression. Everything seemed to be ...
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### Why am I getting a zero parameter estimate and SE for one of my variables in a logistic regression?

I am doing a binary logit analysis, in which I'm trying to fit a model to my data to explain why some towns adopt open space subdivision ordinances (OP), using a handful of discrete and continuous ...
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### How to calculate 95% CI for OR for a different reference category without running the SAS logistics again?

My question is about calculation of confidence interval (CI) for odds ratio (OR) from a SAS output of a logistic regression model for a different reference category without running the SAS program ...
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### Which model to use with repeated measures data that contains multiple binary dependent variables

What model should I use??? I have daily repeated measures data. It has multiple dependent presence absence variables, (of which, I have collapsed into a CA with continuous variables of CA1 & CA2....
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### Predicting ordered logit in R

I'm trying to do an ordered logit regression. I'm running the model like so (just a dumb little model estimating number of firms in a market from income and population measures). My question is ...
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### Is there a better alternative to a logit / probit regression when all dependent variables are dichotomous?

I'm working on a clinical trial dataset with binary response. All independent variables are also binary. My first impulse was to simply run a standard logit / probit regression and be done with it. ...
428 views

### Polynomial kernel in logistic regression?

So I have put together a nice logistic regression program that works quite well. Now, I have used two dimensions to test it and see how it works, and guided by some online tutorials, have increased ...
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### What is the difference between a "link function" and a "canonical link function" for GLM

What's the difference between terms 'link function' and 'canonical link function'? Also, are there any (theoretical) advantages of using one over the other? For example, a binary response variable ...
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### Can I interpret the inclusion of a quadratic term in logistic regression as indicating a turning point?

In a Logistic Regression with linear and quadratic terms only, if I have a linear coefficient $\beta_1$ and quadratic coefficient $\beta_2$, can I say that that there is turning point of the ...
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### How to diagnose multicollinearity using the output of vif function in R?

I am running a logistic regression in R and am attempting to determine if multicollinearity is a problem with my model. When I run vif() on my final model, I get <...
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### How to encode factors as dummy variables when using stepPlr?

When using the step.plr() function in the stepPlr package, if my predictors are factors, do I need to encode my predictors as dummy variables manually before ...
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### Logistic regression on a dataset with duplicated records

I have a large data set with multiple records per phone number. Each record has two variables - the number of past attempts in the past 60 days (number of times it was called) which range from 0 to 30 ...
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### Logistic growth inflection point

I have a logistic growth curve as follows: $y = \frac{1}{(1 + ae^{-bx})}$, where x is the independent measure (x-axis) and a and b are paramaters. The inflection point of this equation is when y = 0....
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### How to determine the best relationship (linear, log, etc.) between input predictor variable(s) and output variable for multiple linear regression?

I am trying to determine the most accurate relationship between two variables (each predictor versus the output eventually). I want to know if the relationship is linear, or log-linear, or log-log, or ...
2k views

### Regression with repeated measures in Matlab

Is there a way to perform multiple logistic regression on repeated measures data using Matlab? I have a data set containing a daily measurement recorded from 20 participants for 60 days. I am ...
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I have $300$ time series objects that constitute the $300$ columns of matrix $X$. This matrix has $5$ rows and represents $5$ days of time series information for each $300$ columns. I set up a \$300\...