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Questions tagged [modeling]

A statistical model is a formalization of relationships between variables in the form of mathematical equations. A statistical model describes how one or more random variables are related to one or more random variables. The model is statistical as the variables are not deterministically but stochastically related.

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Machine Learning Model Selection for discrete inputs and continuous outputs [on hold]

If you have a lot of categorical inputs and a continuous output, what type of machine learning/regression model are suited for that? Thanks!
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Let $y_t$ be a process satisfying $y_t=\alpha+\beta t+\eta_t$ and $\eta_t=\phi\eta_{t-1}+\epsilon_t$.To model $y_t$ under different cases

$y_t=\alpha+\beta t+\eta_t$ and $\eta_t=\phi\eta_{t-1}+\epsilon_t$ Given that $\epsilon_t\sim WN(0,\sigma_\epsilon^2))$. What would you do for modeling $y_t$ in the following cases? $\phi=1$. $|\...
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multilevel logistic regression with rare events

I am running a multilevel logistic regression with a dichotomous outcome. The outcome variable measures protest participation. About 10 percent of the overall sample reports positive answers, which ...
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Three-factor ANOVA

I’m analysing a dataset on contents of flavonoids in different parts of a plant (factor A: leaves, flowers, stems), during different phases of plant growth (factor B: vegetation, full flowering, ...
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how can I interpret a long-run covariance matrix?

can I use the long-run covariance matrix to examine multicollinearity between my independent variables? and if yes, what how can I interpret matrix for determining Multicollinearity?
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Selection optimum polynomial fit

I have fitted polynomial model of orders 1-4. I have three predictors with 7 levels and my response is 400 values from 0.6-0.9, which seems to be bad for information criterions. I am interested in ...
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Longitudinal Study with variable sampling periods

I came across a dataset of a longitudinal study that has the following characteristics: Participants enter at any time in the study They can exit the study at any point for various reasons but cannot ...
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Model interpretation lmer?

I have 139 subjects (ID), with measurements taken at two time points (Time1, Time2), at 148 brain regions, a dependent measure called volume, and a covariate called thickness. Each subject has 148 ...
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Modeling with non-negative skewed predictor

I'm trying to estimate a fractional outcome through weighted logistic regression. One of my IVs is continuous and cannot be negative. And about 45% of the values are 0. Most of the zeros are related ...
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How to model change in independent variable for Cox Proportional Hazards Model?

I'm interested in calculating a time to event model (Cox Proportional Hazards Model) and one of my independent variables has multiple measurements. I'm planning on using a time varying covariate for ...
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Chi-Square - difference in modeling of CI and Chi-square test

If i have a 2x2 table, and i have to calculate the 95% CI for the difference of proportions, and calculate the chi-square test for a 2X2 table For example Learning habits : conventional, e - learning ...
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Avoiding social discrimination in model building

I have questions inspired from the Amazon recent recruitment scandal, where they were accused of discrimination against women in their recruitment process. More info here: Amazon.com Inc's machine-...
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Can I used a General Linear Mixed Model when there are repeated observations for only a small proportion of cases?

I am trying to make a model with a response variable of performance on a test (interval data), along with predictors for test performance. It's a threshold test, so anyone that passes it will not have ...
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What type of regression should be used in predicting Click Through Rate?

I'm looking for a model to predict CTR (click-through-rate) I have the following data: For each ad I know the number of impressions, clicks and some other attributes (which are mainly dummy variables)...
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How to establish the effects of a competitor near my store location?

As part of my studies of statistics, market analysis and data analysis, I’m facing the following problem but not sure if the answer I’m proposing it is correct or not. A commercial retail store with “...
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1answer
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Explaining modelling in simple terms

One of the most challenging ideas to describe to non-technical/mathematical people is "modelling". I've used quite a few explanations so far but all of them were around specific modelling techniques. ...
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Time series model for demand forecasting?

I have a time series $Y_t$ (example:university applications received in a certain month) which I want to forecast. I have another time series $X_t$ and I know that $Y_t$ is related to past lags of $...
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Role of Nested CV as part of Model Development [duplicate]

According to my research, Nested CV is used to estimate algorithm performance without being affected by randomness introduced by hyperparameter tuning. In other words, one should do nested CV to get a ...
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Best way to model the dependency of these two random variables (copula?)

I'm modelling the joint PDF of two variables that looks like this , where vt and vr are the random variables. The dashed line shows the joint pdf assuming they are independent (the product of its ...
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What are Machine learning model characteristics?

This question I have received in some Machine Learning related interview and Here is the question What questions would you ask to learn about machine learning model characteristics? This is what ...
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Modeling relationships between 100+ variables

I have been interested in DS/ML for a few years now and I have been able to build some relatively simple models actually performing pretty well. Now I have this idea in mind but I am not sure how to ...
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Can kinematic equations of motion be considered as a statistical model?

The motion of a car (or a car relative to a lead car) can be modeled using kinematic equations of motion as described below: where, for single car (for a pair of cars) u = inital speed (or ...
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Is my (repeated-measures) multilevel model correctly specified in R?

Objective: I would like to make sure I specified my multilevel model correctly in R using nlme package. Background: I have a ...
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Poisson log linear Regression: using either R or python

I was hoping someone can help me with this problem. I posted a similar question earlier but it's not the same. I have the following: A 2x2 matrix of structural connectivity values between brain ...
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How to model multivariate Gaussians with prior knowledge on covariances?

When modelling multiple variables with multivariate Gaussian, we often assume that the covariance matrix is diagonal to reduce the complexity and computation cost of the problem. In such cases, if we'...
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Model for hormone levels over tissue cells

I have a certain type of biological data and I am unsure about how to model it. The data represent the amount of 3 hormones detected along 20 consecutive cells of a certain plant tissue. I think there ...
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1answer
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Nested linear mixed effects model with time interaction

I am dealing with a fairly complex model in my current analysis and I think that I am not able to model it correctly. My data come from a database in which 40 subjects ...
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How to model multiple training sets?

I'm analyzing the performance of 56,000 binary one-vs-all classifiers to learn how different feature sets affect object recognition performance with extremely limited training data. The data vary on ...
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Choosing statistical analysis with an ordinal DV

I am struggling to determine which statistical test to use for my analysis for my dissertation. I am studying how psychologists and clergy members are taught to work with families where there has been ...
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Which statistical method/test?

I am new to statistics. I want to put the evaluation plan of my research. The research will be in the form of a RCT with 2 groups (Intervention and control). I will be comparing the change of the ...
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What is the most common KIC? How does it work?

Information Criterions are methods of assessing model fit penalized for the number of estimated parameters. Another question on the site asked for a comparison between the KIC and two other common ...
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1answer
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AMOS: Model is unidentified requires 26 additional constraints! How to fix? [closed]

After running model on AMOS I am not getting any output path and this note appears in the text output: "The model is probably unidentified. In order to achieve identifiability, it will probably be ...
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1answer
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Without testing: when are error terms possibly homoscedastic?

I am facing the following study: In the 1980's, Tennessee conducted an experiment in which kindergarten students were randomly assigned to regular and ...
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188 views

Modeling Time Series Sensor Data with Machine Learning Techniques?

I work on air quality sensors, several of which are electro-chemical gas sensors. By way of background, these sensors are stimulated by a potentiostat circuit which applies a bias voltage and then ...
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Default inferential methods for multivariate exploration or model checking

What are your default methods to explore or understand a multivariate relationship between let us say a fixed outcome $Y$ and a limited set of explanatory variables $X_i$ ($i=1,…,n$) (with $k$ not too ...
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Comparing results from Aircraft Trajectory modeling results

I have a set of $>500$ aircraft trajectories. I produced several sets of predictions for these flights using different meteorological models with winds aloft. When I analyze the results of the ...
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Controversiality metric

I am working with some data that needs to be labelled based on preference. Each user can cast one vote that places the item in one category, from 'totally dislike' to 'totally like' (there are 6 ...
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cumulative effect of near significant differences?

My knowledge of statistics is pretty limited at this point, so you'll have to excuse my ignorance. We've performed prospective randomised study looking at the differences in detection rates of cancer ...
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Continuous between participant factors

for my doctorate thesis, I would like to test the effect of behavioural inhibition (continuous variable) on stress reactivity in two different groups that will be separated on their past stressful ...
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Rank Ordered Logistic Regression

In an experiment, I have identified seven sensory parameters of lettuce. Examples are colour and texture. These were ranked by consumers in the order of most important to least important. I also ...
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1answer
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Before running a ridge regression model, do I need to preform variable selection?

I am currently constructing a model that uses last year's departmental information to predict employee churn for the current year. I have 55 features and 318 departments in my data set. A good ...
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Correlation of fitness vs performance on an ensemble model analysis

I have data in the form (the following are just dumb values I use for presentation purposes): ...
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Bayesian hypothesis testing with multiple beta-binomials

I want to test questions relating to whether individual ants of a certain species have personal food preferences, using a Bayesian model built up of multiple beta-binomial distributions. My problems ...
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strictly nonnested models vs partially nonnnested/overlapping - Vuong's test

I'm trying to use Vuong's test to compare LR models - having trouble with the definition of 'strictly nonnested' vs 'partially nonnnested'/overlapping. There are a few (lay language) definitions of ‘...
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how to compare the performance of linear regression vs tree-based methods such as randomforest

When I have linear regression, negative binomial, ridge/lasso regression and randomforest, how can I compare their performances? I've read that between linear regression and ridge/lasso, one can ...
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Why are ROC curves and AUC values not always relevant?

So I have read in posts and in literature (Frank Harrel - Regression Modeling Strategies fx) that depending on what you do, ROC curves and AUC values are not always relevant, but often written in ...
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What is an ablation study? And is there a systematic way to perform it?

What is an ablation study? And is there a systematic way to perform it? For example, I have $n$ predictors in a linear regression which I will call as my model. How will I perform an ablation study ...
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SVM model overfitting?

I have a multi-class (10 classes) classification problem. I am using one-vs-rest SVM modeling with sklearn.svm.SVC. I want to know whether my model is over-fitting. For train set accuracy is 100% ...
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What is a good model for learning power equation against frequency for a chip

Here's my problem scenario:- I have to come up with a power equation as a function of frequency. The plot fits well with a higher order polynomial (4th or 6th) :- $$Power = \theta_0 + \theta_1 fr^1 + ...
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What are some methods to analyse large sets of data in effective and efficient ways?

I have large amounts of data for clients of a transport provider (think similar to a taxi) in and around New York City. The kind of information I have is: What area they are travelling to and from. ...