Questions tagged [model]

A formalization of relationships between stochastically (randomly) related variables in the form of mathematical equations. DO NOT USE THIS TAG BY ITSELF: always include a more specific one.

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5 views

Is it a good way to present updated model coefficients by refitting the model using both derivation and validation data?

I am conducting a research on the development and external validation of a prediction model. I have developed a regression-based prediction model using derivation set data and externally validated it ...
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6 views

Comparison of forecasting models at scale

I am working on a project and 675 models time-series were built. Their variations are related with the intervals to be considered (1 year, 2 years or 9 years), the percentages of the training and test ...
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13 views

Survival Analysis to Forecast Attrition

I have 5 years of historical data. I need to build an model forecasting attrition for the next 3-5 years. I want to build a survival analysis model, but need to know if I can estimate the attrition (...
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4 views

Analytical model, any problem in using independent variables in another model as control variables?

I am conducting a research using Stata using the following analytical model: I run two OLS models: Model 1: VAR 3 (dependent) against VAR 1 and VAR 2 (independent) Model 2: VAR 4 (dependent) against ...
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9 views

doing a cross validation mean squared error on a time series data using fable's prophet

I'm trying to do a time series cross validation with the fable prophet model on an increasing window for training and a h = 1 lag for estimation. Here's my code ...
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10 views

How the last hidden layer of a Neural Network determines the model’s capability?

I recently came across the statement "The dimension of the last hidden layer of a Neural Network determines the model’s capability." from theThe 5 Variants of Multi-Layer Perceptron for ...
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6 views

How to settup a databas for PLS model different scenarios- same individuals

I am currently doing my Master Thesis on how the Willingness to Pay (WTP) and Purchase intention (PI) of customers is affected by the level of customization of a product; I am using PLS-SEM model. ...
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15 views

Can I interpret the signs of coefficients in a VAR model?

I estimated a VAR-model. I checked the time series for stationarity and after estimating the model the residuals and all is fine. I know that it makes no sense to directly interpret the coefficients ...
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24 views

Is using more data in an analysis of variance inherently better?

I have a large data set (~50000 rows) with each row representing one hour of data. I want to know if more tags are detected based on equipment model used. The data represents 90 sites (each site ...
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1answer
13 views

Comparing 2 sets of different survival predictors

I have different predictors for survival data. How can I compare which predictor set would act as the better set? In other words, how can I compare ...
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1answer
20 views

What is the baseline model in structural equation modeling analysis, what it may look like?

I am reading (also learning) a paper using structural equation modeling (SEM) as their analysis method. Their analysis was constructed by using a correlation matrix and asymptotic variances. They ...
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8 views

Can I use the RMSE to compare the two regression model with log transformation and without

I was used the tree diameter data to estimate tree height in the tropical rainforest. We developed a few models, Model 1 - H = 4.32 + 0.27*D Model 2 - H = 1.47 + 0.012 ln(D) Model 3 - ln (H) = 0.84+0....
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19 views

Fit two logistic regressions for two groups separately and Compare them

I want to fit logistic regression with a binary response, and a continuous independent variable (e.g. Age). There are two groups of data, and I want to compare the models between the two groups to see ...
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1answer
21 views

Test Accuracy same as Training Accuracy

I am building a prediction model using KNN. After experimenting the data using KFOLD Cross Validation technique, I've got the mean accuracy and applied them on the real model and it turns out that the ...
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11 views

Averaging repeated measures in ANOVA model

I am looking for an appropriate ANOVA model for the dataset I am working with in the assignment. Specifically, the dataset measures the mortality rate of diabetes per ethnicity group in different ...
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Do these graphs fulfill assumptions of linear model?

Hi, I can see that there is a slight trend in the Scale-Location graph. I'm wondering if this is neglible enough to go ahead with a linear model? thanks! Eamon
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increase precision without hurting recall

I have a classification problem with class imbalance and after the oversampling, I get high recall ,accuracy and roc (around 0.85) while my precision and f1 is fairly low(0.50). I have used every kind ...
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12 views

Check for a disease seasonality

I want to see if there seasonality to a disease Im looking at an autoimmune disease that has several subtypes, characterized by different autoantibodies (lets call them autoab1, autoab2, autoab3). I ...
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11 views

Time series I(0) and I(1) - how do I use it in a model?

I am analyzing two time series with the goal to run a VAR-Model. Now I ran a KPSS-test to test if the time series were stationary. The result is now that one time series is I(0) while the other one is ...
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6 views

Time series I(0) and I(1) - how to model it?

I am analyzing two time series with the goal to run a VAR-Model. Now I ran a KPSS-test to test if the time series were stationary. The result is now that one time series is I(0) while the other one is ...
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7 views

using post production data for prediction

Lets say I have to build a model to predict user's feedback rating for a product. Features used are, F1: user's mean rating for all previous products F2: product's mean rating ... and few more ...
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18 views

Trouble shooting GAM model fitting in R package mgcv - a low P-value

I am using a GAM (in R, 'mgcv' package) ultimately to predict the distribution of seabirds, a separate GAM per species. My response data are discrete seabird counts from strip transects, values range ...
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1answer
52 views

Synergistic effects: what statistics should I use?

I have one control group and three treatment groups. These three groups are treated with substance $A$, $B$, and $A + B$. After treatment, the measurements compared to the control changed by $x,$ $y$, ...
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Linear regression with AR(1) and Dummy

I'd like to do an regression with an AR(1) process and a Weekend Dummy. How can I do this with RStudio? I found out the general formula as $Y_t=a_0+a_1*Y_{t-1} + \text{Dummy}_t + \epsilon_t$ But I ...
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4answers
438 views

Order of variables in R's lm

I dont quite understand the answer given in Order of variables in R lm model in lm() function of R (and generally formulas) why changing the order of variable ...
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1answer
31 views

How would you interpret this result of ANOVA and the interaction plot, where the picture seems to contradict the output of ANOVA?

Let's see the two interaction plots below. It's the same design, just "orthogonally" displayed: The ANOVA says: ...
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15 views

Is it OK to use GEE insetad of GLM for non-repeated data?

I analyse data, that are repeated (pre-post), but I work with change from baseline instead. This is a non-randomized experiment, so I was advised to run this kind of analysis bearing in mind the Lord'...
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1answer
32 views

Fitting model to Wood's lactation curve

I'm trying to determine how I can estimate the following model: $y = at^bexp(ct)$, where $a$, $b$ and $c$ are estimate from a set of data. But I can't figure out how to derive the formula into ...
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2answers
30 views

Can I simply remove one of two predictor variables that are highly non-linearly correlated?

I understood why we should avoid having linearly correlated variables in our model as asked in this question remove one of two linearly correlated variables.\ But should we do the same when we face ...
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19 views

How do I determine the set of all replicable claims?

Consider the one-periode model $(\Omega,F,\mathbb{P},S_0,S_1)$ with $\Omega=\lbrace \omega_1,\omega_2,\omega_3,\omega_4\rbrace ,\ F=$P$(\Omega),\ \mathbb{P}(\lbrace\omega_i\rbrace)>0$. There are ...
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12 views

Why accuracy over each k-fold cross-Validation differ alot? how can i improve that

I have a data set with 91 Obervsation with 700 features. I have reduced the dimension of data using PCA. Then I split the data-set into training and test with ratio= 70/30. After that applied kfold =...
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10 views

Does the model selection in this study make sense?

I was introduced to the following study. It seems to me that they are comparing three groups with a lot of predictors. If this was my study I would have just ran a mixed model or an ANOVA to compare ...
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12 views

Method of Data-Analysis

For my research I'm examining whether applying a certain promotional intervention improves the amount of misshapen products bought. The study contains of two parts. In part 1 Scanner data from ...
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23 views

What is an appropriate model for K continuous parameters on [0, 1]?

Question Summary What kind of model is appropriate for estimating K parameters on [0, 1]? In particular, what kind of joint posterior should a model put on K parameters with support [0, 1]^K? ...
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1answer
28 views

Method of Data analysis

For my research I am comparing actual purchases (in amounts of products bought) in different conditions. I'm examining whether applying a certain promotional intervention improves the amount of ...
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1answer
35 views

Estimating the true nonlinear regression parameter with parameters from multiple specimens

I have collected data on the stress relaxation ($\sigma$) of 3 chicken tendons over time ($t$), and the following nonlinear regression model was fit through each individual tendon: $$\sigma = A + B e^{...
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0answers
20 views

Data Analysis, find the best city for given individuals

I'm trying to solve a data analysis question where I'm given data on ~1000 cities. For each city, I have: the average property tax, rating of schools nearby, crime rate, avg number of rooms per appt ...
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1answer
22 views

Using ML model on biased data

Have ML model (gradient boosting) trained on n features. For example, one of these n features is region. Looked at feature importances - it is one of the most important features (by split). The ...
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26 views

A method to avoid running several regression models?

Sometimes I have a research question where I have maybe 10 different outcomes and I am interested in whether any of these 10 outcomes are associated with several other variables, such as weight, ...
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31 views

multiple regression model - interpreting graphs for the fit [duplicate]

I have the following r code. I created a multiple linear regression model on a math_and_alcohol dataset. I can see in the summary of the model that the r-squared is .8279 which means the model ...
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1answer
122 views

Difference in Differences Model Specification with Year-Quarter Effects (treatment non-binary)

I am currently creating a difference-in-differences (DiD) model and have a few questions left: I am examining the effect of Airbnb-listings on the hospitality industry in major German cities. I have ...
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1answer
24 views

How to get coefficients from exponential model [closed]

I have data $y$ (contain some NA) and $x$ and i want to fitted an exponential model that follow the function: $$y=A \exp(B\cdot x)+C$$ What function in R that can estimate the value of $A$, $B$, and $...
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4 views

Open source pre-trained models for taxonomy/general word classification

given any two words I'd like to understand if there's some sort of taxonomy/semantic field based relationship. For example given the words "Dog" and "Cat" I'd like to have a model ...
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1answer
30 views

Avoid trial field test using previous data: use of chi-squared test to show that carcass removal do not change significantly over time

I am implicated on the analysis of mortality rates of bats and birds in wind farms. For this purpose, I need to go to the field and count the number of carcasses found around the turbines. However, ...
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14 views

How to fit a zoib regression model with random effects from zoib package

Sorry for this likely basic question, but I have been trying to use the 'zoib' package for a while and seem to be unable to do so. I just want to fit a univariate model with random effects on batches, ...
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25 views

Predict parameters of another model

I would like to make a model to predict the parameters of another model. As example, By using design of experiment I made some trials and I measured the temperature (response). e.g. ...
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7 views

Can k-fold CV help reduce sampling bias?

I am currently writing a thesis and have surveyed about 500 people and I am using it as input in a supervised model. Due to some time limitations there was some bias in the sampling process itself. I ...
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1answer
23 views

Using repeat measurements to increase validity?

User Dave posted an answer to a relatively simple question, but with an interesting twist in the comments. Here, the idea seems to be to run repeat measurements on random samples, drafting a histogram ...
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17 views

Solution to a single feature logistic regression problem [duplicate]

So I'm having a hard time conceptualizing how to make mathematical representation of my solution for a simple logistic regression problem. I understand what is happening conceptually and have ...
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2answers
402 views

Why do we write models in the form of E(Y)?

A linear model is given by $y=X\beta + \epsilon$. Why do we often instead write it as $E(Y) = X\beta$?

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