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Questions tagged [modeling]

This tag describes the process of creating a statistical or machine learning model. Always add a more specific tag.

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When working with real life data, how do you handle many missing/NAs in columns for modelling? [duplicate]

I'm kind of a newbie in this regard and having trouble understanding or how to deal with it. I work with a lot of patient data and this data comes from nurses/doctors about how patients are treated. I ...
Mahix's user avatar
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Does it make sense to include both age and birth year as covariates in a model?

A researcher asked me about adjusting for both age and birth year in a model. To my mind these are perfectly collinear, but then it got me started looking around online and down the rabbit hole of age-...
LucaS's user avatar
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5 votes
1 answer
604 views

Would it be possible to generate data from real data in medical research?

We are trying to develop some predictive models in medical research. We have combination of clinical and RNA-seq data just for 40 patients. The problem is classification. After feature selection, we ...
Leila ali's user avatar
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Would it be possible to use regularization methods as a feature selection method and then use machine learning models to analyses data?

My data is RNA-seq data with more than 14000 features and the problem is binary classification. Then the total sample is 50 and p>>n. When I use Elasticnet method with train and test data, the ...
Leila ali's user avatar
0 votes
1 answer
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Is differential follow up periods in survival analysis a problem?

I'm looking to compare mortality post-operatively following two different surgical techniques. due to technological advances, one of these surgical techniques was only performed around five years ...
MFA's user avatar
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Is factor with two levels set as random effect okay in GAMs? [duplicate]

a. Can covariate that are factors/categories that have 2 levels, such as yes/no or presence/absence, that also change spatial location from year to year have a smooth basis of “re” (bs=re)? Should it ...
frog_dan's user avatar
2 votes
0 answers
24 views

Using whole training set for choosing model

I am working on a classification problem with what I understand as a big dataset. I have first of all splitted it in my "train" dataset and the "test" one. (Actually I am convinced ...
Videgain's user avatar
2 votes
0 answers
20 views

In MVGAM, how can I model an interaction between 1 continuous variable (Abundance), 1 discrete (time in days) and 1 factor (the Genus of eukaryotes) [closed]

I'm working in microbial ecology and I'm trying to modelize the influence of the abundance of several genuses on a single genus of interest through time in a situation of primary succession of ...
Samuel beauregard-tousignant's user avatar
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0 answers
9 views

Repeated-Measurements Analysis with Cross Correlation

I am trying to find the cause-and-effect relationship between water release from dams and downstream temperature. I have a data frame containing all of the temperature measurements from various sites ...
Matt Schaaf's user avatar
0 votes
1 answer
20 views

Using a model to evaluate over or under-priced rental prices for the same apartments used in training

If I have a machine learning model which predicts the rental prices of apartments, can I use the model once complete to analyse the prediction for the same apartments I used to train the model so I ...
AWGIS's user avatar
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5 votes
1 answer
194 views

Why in ordinary linear regression is no global test for lack of model fit unless there are replicate observations at various settings of X?

I read this quote from Regression Modelling Strategies. In ordinary linear regression there is no global test for lack of model fit unless there are replicate observations at various settings of X. ...
Geoff's user avatar
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3 votes
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How to Automatically Identify Column Headers in New Datasets Using Machine Learning?

I have a dataset with vehicle data that includes headers (example): I receive new datasets with similar vehicle data but no column headers: I need to create an algorithm to recognise and assign ...
user782750's user avatar
1 vote
0 answers
86 views

Estimation in generalized additive models

I'm currently trying to learn about generalized additive models (GAMs) with the book Generalized Additive Models An Introduction with R by Simon N. Wood. However, I have some questions regarding the ...
Dude3400's user avatar
4 votes
2 answers
87 views

Comparing matched pre-post likert scale data (n = 40)

I have pre-post matched likert scale data (~20 questions) that I need to analyze. 1) What is the best way to analyze these data? I initially thought it would be ok to use means and do a paired ...
LIz's user avatar
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What methods to use for statistical analysis of a network structure?

I have a network structure (adjacency matrix) and want to find a method that tells me which features of my network are most important to explain my response variable. In this case its an infection ...
Nitara Wijayatilake's user avatar
1 vote
1 answer
91 views

Repeated Measures Analysis of Variance Question

I have the following data set. ...
David Moore's user avatar
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36 views

How to set up a Bayesian model properly - an example with a smartphone dataset

I'm starting with Bayesian modeling. In the book Learning Bayesian Models with R by M. Kodulevy there's an exercise based on a UCI dataset (chapter 3, ex. 2). The exercise goes like this: there are ...
Jakub Małecki's user avatar
4 votes
1 answer
45 views

Measurement invariance and latent mean comparison between 3 groups

I performed an Exploratory Factor Analysis (EFA) followed by a Confirmatory Factor Analysis (CFA) in R, successfully assessing the model fit using indices such as TLI, CFI, RMSEA for a two-factor ...
DavidP's user avatar
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1 vote
1 answer
32 views

How to correctly specify "exposure" and "outcome" in dagitty/ggdag, when modelling the inverse relationship (exposure ~ outcome)?

I am trying to use the package ggdag in R to better understand the results of my modelling. If I wish to model the relationship ...
Ildifa's user avatar
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0 votes
1 answer
47 views

Advice Desired: Predicting US Tornado Counts Via Multi-Level Model

I wish you good health and the best in life (whatever that means for you in particular). Context I want to model aggregated (monthly) tornado counts in the United States for a question on Metaculus. ...
FilteredFrames's user avatar
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Are observations of different plots of the same farmer independent for a chi-squared test?

I have a pretty basic question. I have a dataset that has surveyed say 1000 farmers and their demographic data, and also surveyed the agricultural practices they undertake on each of their plots. Only ...
cha116's user avatar
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2 votes
0 answers
28 views

Testing time series data stationarity

I am working with time series and want test different forecasting methods but first I need to test if my time series (sales) data is stationary or not. So I have been learning about KPSS and Dickey-...
monique's user avatar
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0 answers
17 views

Utilizing bipartite network information in standard regression analysis

The gist of my somewhat general question is if there are some useful approaches to utilize information about relationships between individuals embedded in a bipartite network when the goal is a node-...
Denzo's user avatar
  • 602
2 votes
2 answers
47 views

Data modelling as a surface

I want to model waste generation in a city using data from the containers. I have the location and fill levels of each container over time. My idea is to use the average amount of waste in each ...
pato's user avatar
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2 votes
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80 views

When authors write "model of the data" is this a shorthand for "model of the data generating process" [duplicate]

Some authors, such as Barber in Bayesian Reasoning and Machine Learning and Rasmussen & Williams in Gaussian Processes for Machine Learning, write phrases such as "model of the data" and ...
fire-bee's user avatar
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0 answers
76 views

Handling the situation: (x ~ y) == (y ~ x)

If fitting the following two models, using linear regression, produces coefficients that are essentially the same, what is the appropriate modelling technique to use? ...
Derek Jones's user avatar
1 vote
1 answer
98 views

Independent variable becomes insignificant after adding control variable. Mediation is significant but doesnt make sense

I am doing a linear regression analysis and have the problem as stated above. When only the independent variable (IV) and the dependent variable (DV) are included in my model, I get this: ...
user9011032's user avatar
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0 answers
14 views

Classification model for categorical data, highly imbalanced

I am trying to create a classification model for birth defect data. The goal is to determine which of the paternal variables are most associated with the top 5 birth defects. The target variable '...
Farmurey's user avatar
2 votes
0 answers
37 views

What is the role of determinism in stochastics?

What is the role of determinism in stochastics? In my opinion, determinism, much like the continuum, is merely a concept to describe an ideal world. In this idealized world we can calculate and argue. ...
Henning's user avatar
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0 answers
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in ann model statistical calculation can mae be greater than rmse? [duplicate]

in ann modelling creation can mae be greater than rmse? i am using the LMNN algorithm for creting the ann model.i am having the values as said above in the performance evaluation of the ann model.can ...
Tapaswini Mohanty's user avatar
5 votes
1 answer
45 views

Very basic questions about choosing weights for WLS

Hi all – very new to stats and ML here (though with plenty of math experience – I’m not a student looking for homework help, I’m 58, know plenty of math, and am looking to expand my skills).

I ...
Steve Lane's user avatar
1 vote
0 answers
18 views

right way to include time variable

This questions is about what is the right way to include time variable in model. I will start here. I have two outcomes, Continuous [time until seed germination] Discrete(binary)[seed germinate Yes/...
Science11's user avatar
  • 577
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0 answers
11 views

Does anyone have a name for a model that is by nature in a feedback loop?

I'm hoping someone could help me find some literature on a situation I'm dealing with, even if it's just by providing a name for what the system is called. Also, it is entirely possible I'm imagining ...
Nye307's user avatar
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0 votes
0 answers
22 views

Combing multiplicative and additive effects in GAMs or GLMs

I am currently modelling a data set of house sales prices, P, as a function of various characteristics such as location, house size etc. etc. The list of explanatory variables can be divided into two ...
August Edwards's user avatar
4 votes
2 answers
58 views

Accounting for recall period in proportion meta-analysis

We are conducting a meta-analysis of "prevalence" of event-type exposures, e.g. "have you been physically assaulted in the past X months". We are trying to adjust for different ...
jessexknight's user avatar
2 votes
1 answer
42 views

Distribution of conditional waiting time untill next event in a renewal process [duplicate]

Let $J_n = \sum_{i=1}^n S_i$ be a renewal process with gamma distributed interval times $S_i \sim Gamma(\alpha,\beta)$. Consider the value $J_k$ of the first event when the process passes a certain ...
Sextus Empiricus's user avatar
1 vote
1 answer
40 views

question about including an independent variable

I'm seeking advice on whether to include the independent variable 'smoking' (Yes/No) in my analysis. The objective is to examine the impact of COVID-19 on female construction workers. The outcome ...
Science11's user avatar
  • 577
2 votes
0 answers
25 views

Modelling consecutive Poisson point processes, where the second starts only after the first has x counts

I'd like to model a situation where there are 2 consecutive Poisson point processes with different event rates, and the second process only starts after the first process reaches a cumulative event ...
abcoxyzide's user avatar
5 votes
1 answer
73 views

Assessing the relationship between two variables

I've been trying to analyze the possible association between the number of questions done while studying and the average result of users after several testing sessions. The ...
Pedro Alonso's user avatar
1 vote
0 answers
29 views

Statistical Modelling Research Papers

My task was to make a logistic regression model for a dataset to predict a binary variable (0/1). During this process I went through all of the stages of model building, from scratch given unprocessed ...
Alex Smirnov's user avatar
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0 answers
36 views

Mixed model realized value of random variable

In Andrew Gelman's book "Data Analysis using Regression and Multilevel/Hierarchical Models" , page number 258 group $j$ random intercepts $\alpha_j$ is estimated based on this expression $$\...
Sundown Brownbear's user avatar
0 votes
0 answers
10 views

Modelling count from frequency

I have an empirically derived frequency curve. From the curve, I aim to model counts per unit time. The x-axis is diameter, and the y-axis the likelihood of observing the diameter per one year. I ...
Eron Raines's user avatar
6 votes
2 answers
206 views

exclude random effects component for a repeated measure

I'm analyzing a dataset on the Nurse Licensure Exam, comprising 3000 participants. (n) These 3000 participants were randomly recruited from 13 Sites across the US. (group level variable) About 40% of ...
Sundown Brownbear's user avatar
0 votes
0 answers
17 views

Approaching regression analysis given all correlation is low [duplicate]

A question on approaching regression analysis when all Y - X correlation is low; almost all |correlation| < 0.1 To give an outline of data I have: Y (Store sales by month); n>2000 Xi (Macro-...
Jun's user avatar
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2 votes
0 answers
32 views

Choosing between Negative Binomial, Zero-Truncated NB, and NB with Arithmetically Altered Outcome (SAS)

I am modeling longitudinal Days of Pill Supply with predictors Number of Rx's and Patient Race. I was not able to use linear regression (proc reg or proc glm) because of heteroscedastic residuals, so ...
L.S.'s user avatar
  • 341
5 votes
2 answers
48 views

Choosing the right modeling procedure

I am working with a dataset (electronic medical record extract) and trying to find out whether there is a difference in a continuous integer outcome (RxTotal, mean=7.4, range 2-34, skew=1.6, kurtosis=...
L.S.'s user avatar
  • 341
3 votes
0 answers
41 views

Can a Gaussian Process predict random events?

I know that we can use Gaussian processes effectively for function approximation and regression. However,suppose there is a sequence of points in time $S = \{s_1, s_2, \dots, s_n\}$, where $s_i$ can ...
Hassan Ali's user avatar
4 votes
1 answer
437 views

Model assumptions - not worth the effort?

This question was inspired by this discussion I read recently. After obtaining our results, the assumptions from the models we used should be checked, otherwise these results may be deceiving. ...
JED HK's user avatar
  • 409
0 votes
1 answer
35 views

The Concept of Mixed-Effect Modeling in Gardening

I have random factors such as Flower, Allotment and Gardener. Gardeners scored the flowers. Flower Crossed in Allotment. Flower Nested in Gardener, and Allotment Nested in Gardner. Can I analyse each ...
user330's user avatar
  • 218
4 votes
1 answer
293 views

Probability distribution for weights in Gym machine?

Below is the image of weights in Gym, I would like to know what probability distribution that would fit the wear and tear of the weights. Below are my initial thoughts: (1) Has to be discrete ...
forecaster's user avatar
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