# Questions tagged [regression-strategies]

Regression Modeling Strategies

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### Autocorrelation of journeys along a route

I have a data set where I have journey based data from buses, and how long time it took to travel a said bus-stop (starting from stop 4). I have multiple such journeys recording, and they are kept in ...
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1 vote
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### Analysis with data from different sources

I have data from 3 different sources, measuring different variables for different samples taken from the same population (a country). All of the data is from country-wide studies and should be ...
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### With what argument can I use splines method in a binary logistic regression analysis?

I want to run a binary logistic regression and I guess some variables have nonlinearities. So I want to use splines method to understand affect of each range in a continuous variable. When I 'guess' ...
64 views

### When fitting a generalised additive model, how to choose how much to smooth?

When fitting a GAM, is there a rule (of thumb) for deciding if $k$ (max number of degrees of freedom for a spline) is large enough or not? How much should edf be below $k'$? And is that an absolute ...
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1 vote
86 views

### Breaking the regression line into two pieces

My X & Y variables are associated like this below and I am trying to fit a simple linear regression model (y ~ x , data= df) , to estimate ...
• 409
1 vote
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### pmin(x, 60) and subset regression [closed]

Is there any difference between y ~ pmin(x, 60) + sex , df = data and y ~ x + sex, df = subset(data, x <=60) If they are ...
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23 views

### Is it okay to run multiple regressions for each level of a predictor? [duplicate]

Suppose I want to test the effect of stress on the amount of uttered insults in three groups (psychologists, doctors and lawyers). The most direct thing that I can come up with would be a Poisson ...
90 views

### How damaging to the analysis would it be to run probability validation (rms::val.prob) when calibration (rms::calibrate) is the correct action?

If I make a model that predicts probabilities (e.g., logistic regression or a neural network), I would like it to have the property that, when it predicts a probability of $p$, the event happens about ...
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1 vote
69 views

### How to compare the expected change in a exponential decay function with the expected change in a square root function?

I have two two datasets. Each contains two variables. There is one variable that is present in both datasets. When I plot each dataset to see the relationship between the two variables in each, I find ...
• 1,218
42 views

### Change per capita, logarithmic change or non logarithmic change?

I am currently working with Covid-19 key figures such as registered cases of infection and death. My data is a panel dataset across time and municipalities in Denmark, the set consists of several ...
1 vote
783 views

### Walk through rms::val.prob

The val.prob function in the rms R package has similarities to the ...
• 46.7k
1 vote
2k views

### Walk through rms::calibrate for logistic regression

The calibrate function in the rms R package allows us to compare the probability values ...
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125 views

### Can I interpret coefficients for "Year" as differences between years that are not explained by my predictors?

I am doing statistical analysis of a natural experiment that consists of multiple years of measurements. I have two independent variables that are physically related to ...
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### Meaning of interaction with %ia% in rms? Three-way interaction?

In this very illustrative post on evaluating added value of predictors by Frank Harrell, he codes a logistic regression model as such: ...
176 views

### Estimating regression optimism using the bootstrap

I am estimating optimism bias in for example risk predictions. A method for doing that is described by Frank Harrell and implemented in the R package rms. I am ...
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### Articles about data analysis workflow

I am a non-statistician. I have to write a non-English article about my data analysis workflow for a particular epidemiological regression analysis that I conducted. The article will cover my workflow ...
82 views

### Effect size derived from LME longitudinal model: the statistical findings projected back down onto a group of people

I have been studying the change in a metric X with a linear mixed effect model. I have built this model in a multivariate setting, so I can see how each of my covariates (Time, sex, age) affect X. ...
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1 vote
19 views

### Modelling strategies for analyzing an effect of a predictor through higher hierarchical level

What strategies can be considered when a predictor's direct effect can not be measured directly due to unmeasured confounding? However, data has a hierarchical structure (patients within regions) that ...
• 2,003
1 vote
72 views

### Applying count models with rate responses

How do you apply count models to data which is count in nature, but a rate in reality? In such cases, r can handle this to a certain extent, depending on the model, but what is the correct way to ...
• 209
680 views

### Boruta Algorithm for Logistic Regression?

Is it okay to use a Boruta algorithm to select features for a logistic regression? I read several sources, including the source package as well as this site explaining what Boruta does. My ...
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351 views

### Logit Regression and F-test: Can I apply the f statistic when variables are non-normal and the output is binary?

I want to do a univariate analysis on a set of variables to see which predict a binary outcome. I want to discard some of them before performing logistic regression. I am trying to understand if I can ...
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1k views

### External validation of a published Cox PH model

My aim is to externally validate a risk prediction model published in the medical literature that is based on a Cox regression model. I have a dataset with all the variables from the score. I read ...
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664 views

### Brier score of calibrated probs is worse than non calibrated probs

The question is related to probability calibration and Brier score I have faced with the following issue. I have Random forest binary classifier and then I apply isotonic regression to calibration of ...
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10k views

### Handling missing data in logistic regression

I'm trying to do logistic regression, but I can't seem to get the results I want. I have 6 columns of data (one dependent and 5 independent binary variables) and about 100 rows. The problem with my ...
643 views

### probability calibration and Brier score

Assume that I have a binary classification problem. The outcome from classification I am mostly interested in is the well-calibrated probabilities. The first way to check this is the calibration plot (...
• 386
1 vote
43 views

We have developed a basic Regression framework where we try to build models for over 100 configs(stored in a file). To run : ...
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120 views

### OLR with rms: proportional odds assumption

I am fitting an ordinal logistic regression model with rms package. my data involves a three-level ordered outcome (see ...
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547 views

### When LASSO selects only parts of a categorical variable?

I want to use LASSO to construct a model and then run a logistic regression on the variables LASSO selects. However, LASSO selects only parts of some categorical variables that I put into it. Does ...
• 2,071
1 vote
303 views

### Excluding the effect of control variables in the assessment of a logistic regression model

I have a logistic regression model with ten independent variables of which two are included as controls. While their inclusion is necessary for correctly assessing the coefficients of the other ...
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132 views

### Using "moderately" correlated variables to select controls for a LASSO regression?

In medicine we often have a disease status as an outcome variable and a lot of independent variables in which we want to see if there is some connection. Traditionally, baseline characteristics such ...
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128 views

### How to validate Generalized Least Square model for longitudinal response

I have a dataset with body weights before and in the follow-up visits after surgery, for a group of patients with obesity. Our goal is to fit a model to predict weight loss throughout the follow-up. ...
1 vote
33 views

### Combining mean differences in regressors and significant prediction and moderation in multiple regression

I am analyzing a survey about career choices with an eye toward demonstrating sex differences in: 1) the means for factors that might be related to career choice (e.g., differences by sex in ...
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892 views

### Conducting a subgroup analysis with regression modeling

I'm conducting a survival analysis using Cox Proportional Hazards regression to identify prognostic factors for cancer patients. My covariates include information such as age, sex, tumor location etc. ...
1 vote
22 views

### how to choose the best logit model [duplicate]

I have two logit regression models with different AIC. I'm using R. my first model has significant variables and AIC 192.7436. And my second model has 1 non-significant variables but with smaller AIC ...
1 vote
23 views

### I have a confusion between using 4 different general linear models and 1 singular ones. I have provided with the codes and outputs

I want to check the effect on mass of crickets, I have a fixed linear effect (AltitudeAge), fixed quadratic effect (AltitudeAge^2), random effects (Nymph IDs, population and the incubators they are ...
1 vote
2k views

### Number of Covariates in Cox PH Model and Overfitting

I have a small time to event dataset (N=20) where patients are given one of two drugs (drug) at varying doses (...
264 views

### Fitting model again after variable selection

This question has been asked quite a bit in other contexts (doing LASSO then OLS on selected variables for example), but I'm unsure about how to proceed for this case. Suppose I have a set of 50 ...
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### Problems from having too many interactions in a regression?

Excluding the 'dummy variable trap', are the problems from including too many interaction terms in a regression any different from the problems of including too many continuous or binary variables in ...
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1k views

### Does LASSO suffer from the same problems stepwise regression does?

Stepwise algorithmic variable-selection methods tend to select for models which bias more or less every estimate in regression models ($\beta$s and their SEs, p-values, F statistics, etc.), and are ...
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1 vote
109 views

### Kaplan Meier Diagnostic Utility

I'm trying to understand a paper that claims to have identified a gene expression signature that can distinguish primary from metastatic tumors. The authors stratify their data into patients with and ...
1 vote
303 views

### Logistic regression with repeated mesures and unique outcome

I have one independent continuous and time-dependent variable X, repeatedly measured (from 1 to 4 times) in different patients during some period of time. My dependent variable Y is binary and is ...
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2k views

### Interpretting Cox Regression ANOVA

I'm having difficulty interpreting the results from anova() in the rms package. My confusion arises from what information the <...
779 views

### Interaction between dependent and independent variable

I am conducting a multiple linear regression on data from a cross-sectional study, and I suspect that there is an interaction between my dependent variable (a disease risk marker) and one independent ...
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### How to reduce predictors the right way for a logistic regression model

So I have been reading some books (or parts of them) on modeling (F. Harrell's "Regression Modeling Strategies" among others), since my current situation right now is that I need to do a logistic ...
• 1,017
783 views

### How to perform cross validation in semi-supervised learning

Suppose in semi-supervised learning, we have labeled set $X_L$ and unlabeled set $X_U$ Is it ok to validate model performance on labeled data only? How to do cross-validation in transductive learning,...
1 vote
51 views

### Method for testing interaction in regression analysis

I am running a linear model with 6 explanatory variables (5 in classes, 1 quantitative), and would like to test which interaction(s) are eventually significant. I think an ascendant stepwise method ...
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26 views

### Trying to test if an increased rate of use decreases total product

TL-DR: The higher the rate of production on my expendable unit, the less overall product it seems to produce in its lifetime. I want to know how best to model this or 20 pages I could read which would ...
211 views

### Why do we even bother running regression models?

I'm working through regression with Intro to Statistical Learning by Hastie, Witten, James and Tibshirani. They break down regression into stages: data cleaning and processing, model building and ...
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