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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25 views

Logistic regression vs segmentized logistic regression

This might be a very rookie question. I need help interpreting the results of my logistic regression. Assume I have the following model: y ~ categorical + numerical...
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Specifying interactions as predictor variables in a GLMM R formula - correct method?

I am modelling insect count data as a GLMM of distance along a transect (the length of a growing tunnel (m)), temperature along the tunnel and external daily max temperature, ie in R- Insect_count ~ ...
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Two-Part Model. Packages in R or Python [on hold]

In A Colin Cameron's and Pravin K. Trivedi's Book "Micoreconometrics Methods an Aplications" page 545 the two-part model is defined as: Does anybody know an R or python (preferably) Library that ...
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9 views

Regressing age-specific outcome for individuals born in successive years from biennial longitudinal survey

My question is about a regression model. I am using longitudinal survey data on individuals born in successive years that is collected every two years (in even years) from interviews. I want to ...
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1answer
37 views

Modeling non-linear (short) time series and cross-validate them

beginner data scientist here. Time series analysis is a completly new area for me, so please correct me if i write something that makes no sense. I have many multivariante short time series, between ...
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1answer
30 views

How do you force lm() intercept to be 0 but not remove the intercept term from coefficients? [closed]

I need the intercept of my linear model to be 0, but I do not want the intercept term removed from the model, or the output of the model. I am using the output later in a simulation. Both methods of ...
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1answer
37 views

Waiting time distribution parameters given expected mean

I have a set of healthcare providers serving patients. In a given amount of time, a specific provider can see only a certain amount of patients, depending on the medical procedure and other variables. ...
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41 views

What is the likelihood for this process?

A patient is admitted to the hospital. Their length of stay depends on 2 things: The severity of their injury, and how much their insurance is willing to pay to keep them in the hospital. Some ...
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How can I calculate the exponent (parameter or tail index) of the Pareto distribution associated to the following paperclips experiment?

The experiment is the following: take a pool of paperclips for which in each round we follow these steps: 1) choose two paperclips randomly 2) if they are not linked with each other then link them ...
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1answer
18 views

Change in X and Change in Y in Pearson Correlation

Suppose I have my x variable calculated as Hormone2-Hormone1 where Hormone2 is at a later time point and Hormone1 is earlier - this is true for all subjects and the time points are equally spaced for ...
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32 views

Estimate total effect of treatment when continuous treatment variable and its dichotomization show contradicting impacts

I am trying to estimate the total effect of a leak of a harmful gas on my dependent variable. While I do not know the actual exposure, I know the distance of a household to the origin of the leak in ...
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1answer
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Comparing model performance. What model should I run for this? Confused between Randomized block or Repeated measures

I am trying to analyze some results I have generated from multiple different models. I have 21 models which are all used on the same 9 sets (years) of data. The response variable is the result of the ...
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How can I maximize revenue given a distribution of order totals?

I need help with a statistical modeling problem in R. I want to determine the optimal shipping policy (i.e. free shipping minimum and standard ship rate) to maximize revenue for an e-commerce site. I’...
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22 views

Include main effect when specifying varying coefficient models with GAMM?

I am trying to model an interaction between two continuous variables in the GAMM framework using gamm in R. For simplicity's sake, I am ignoring the repeated ...
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13 views

Modelling births as an outcome of population diversity as opposed to population size

I wish to model and estimate the relationship between population diversity and births (or birth rates) across populations, with panel data, and I face several challenges. 1) Births, population size ...
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1answer
37 views

What statistical model should I use?

I am trying to create a statistical model for my research. I am dealing with a surgery that has the chance of causing damage to the patient. I have found 5 signs, which I believe are indicators that ...
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1answer
24 views

Churn Model Performance Measurement Metrics & KPI For Business

I have a customer churn model, which classifies people who are going to leave (Yes) from those who are staying ...
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20 views

Weighted MLE for more accurate fitting of extreme values?

I want to fit a 3-component exponential mixture distribution to some data that's clearly over-dispersed relative to the standard exponential. Regular MLE works reasonably well, but it doesn't model ...
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15 views

Is is possible to estimate a mixed logit model with only individual specific parameters?

I am analyzing some data and I do not have any alternative specific variables in the dataset. The question is about the preference between taxi, uber and automated vehicle if all three have the same ...
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1answer
28 views

Exploring a loan data set when I'm interested in change in number of loans over time, not acceptance/rejection, defaulting, etc

This is a simple question but I am having difficulty wrapping my head around it. I have a dataset listing a bunch of individual loans. There are tens of variables describing aspects of the loans, mix ...
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1answer
45 views

Number of Regressors in a Regression

I am building a model in R and want to perform some regressions (probably Poisson regression). My problem is that I want to introduce about 330 dummy variables (entries only "1" and "0"). Is that ...
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20 views

Pre post intervention analysis

I have a theoretical question about a fabricated before-after analysis with Intervention and Control groups based around a new testing method. In addition to the treatment groups and time (before and ...
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4answers
81 views

Should I remove the intercept when regressing against one variable (country income)?

I understand that one should not remove the intercept, unless there is a very special circumstance. (see: When is it ok to remove the intercept in a linear regression model?) However, if I am running ...
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0answers
11 views

Strategies for balancing the test/train split for modeling applications?

I am about to embark on a modeling project where I want to split up my data into test and train groups. Initially I was planning on doing a random assignment of each record according to an 80:20 ...
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2answers
66 views

How to modify a linear regression model when the variance is not constant?

I have a very basic question. I have a model that has residuals that don't follow a constant variance pattern, but rather it has a clustered pattern (see the figure attached). Any idea of how to deal ...
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0answers
37 views

Which model type for a distribution of discrete outcomes?

I am doing work on predicting household types (income group, number of workers, presence of children) based on a forecast of a number of economic variables from a regional economic model, such as a ...
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Conceptually, what makes a convincing case for researchers to add an extra predictor to their models?

Here is a thought-example to make things easily understandable: Let's pretend that researchers often use a paradigm where half of a series of objects are shown to participants' left eye and the other ...
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Logistic regression or linear probability models

Here, I will ask a question which always seemed trivial to me as an application focused person studying political science: Do I use a logit model or an LPM when modeling categorical data? Up until ...
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1answer
40 views

Stata xtlogit, pa vs logistic

I'm a grad student with a moderate statistics background having a bit of trouble figuring out which binary statistics model to use. I have a dataset with repeated measures of patient lab values at ...
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1answer
130 views

Decomposing U.S. Imports of Goods by Customs Basis from China

I'm working on a project which aims at analyzing the dataset U.S. Imports of Goods by Customs Basis from China (IMPCH). The main point is to make some prediction but we also want to do a little ...
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0answers
13 views

Do I choose the logistic regression model with the better F1 statistic on the validation set or the lower AIC?

I am deciding whether to keep an interaction term in my logistic regression model. If I keep it in, the AIC of the model improves. If I leave it out, I get a better F1 score with my validation set. ...
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1answer
33 views

Repeated measures in a mixed model

I'm trying to fit a mixed model for data from different medical centers, where "center" is thought of as random. I have data over 2 years on how many patients they receive each day. I have several ...
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0answers
22 views

Estimate Particle Density from Image Analysis

Suppose I have an old image of an object where the objective is to estimate the mean particle density of said object. Using a software called ImageJ, I am able to run a thresholding algorithm to ...
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34 views

Relationship between two categorical variables

I have collected data for Dish Name, Cooking Method, Type of Dish, Cuisine and Nature ( given below ). I am trying to find out relationship between Cuisine and Type of Dish. I have tried to implement ...
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1answer
26 views

Which trigonometric function I should use to generate the temperature with two peaks (i.e.one strong and one moderate peak)?

I want to generate seasonal temperature of Bay of Bengal. I want to do this with a trigonometric function. Seasonal temperature of Bay of Bengal has two peaks. One major peak during April and another ...
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3answers
35 views

Generating a measure from percentage frequencies

I have percentage demographic data for the various areas of the US which is broken down into 5 buckets: Child, Teen, Student, Adult and Retired. So for example for Texas, I have: Child: 0.2 Teen: 0.2 ...
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1answer
25 views

Label encoding vs Dummy variable/one hot encoding - correctness?

i understand that when label encoding is used, the numeric number can be interpreted to have an order and a model could assume a linear relationship. However shouldn't this be a problem when there are ...
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0answers
62 views

Predict periodic event with multiple guesses and re-alignment

Suppose there's a metronome set to 60 bpm. Without hearing or looking at the metronome, we need to predict when it ticks. A prediction is considered correct if it ...
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1answer
16 views

Probability of getting a negative mark if one chooses options randomly in a MCQ question with negative marking

In a test with 100 multiple choice questions, a student chooses to pick an option randomly. There are four options for each questions. Answering a question correctly will give the student 1 mark, ...
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1answer
58 views

Validity of Weibull distribution [closed]

I have come across validation engineers picking the Weibull distribution as a way to generate test stimulus. When they do this, they seem to chose the parameterisation without reference to any ...
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0answers
14 views

Modelling probability distribution of a set of sequences (to calculate Entropy)

Let $T$ be a set of trajectories $\tau$, where $\tau=\{\mathbf{x}_1,\mathbf{x}_2,...\mathbf{x}_N\}$ with $\mathbf{x}_i\in\mathbb{R}^k$ being a vector of observations. I am looking for an efficient ...
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1answer
13 views

How to model a distribution from simple capital cost data?

I want to create scenarios for a simulation model I am working on. Someone recommended me a distribution and select instances to create different scenarios. But my data is limited. For example, my ...
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0answers
32 views

How to model a specific distribution using domain knowledge rules [closed]

Suppose I have a variable Y that I want to predict with a model using predictor variables X1, X2 and X3. I have a large set of Y-data and from this I know with some certainty and accuracy the ...
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2answers
49 views

how to analyze time series data and mark if single data is seasonal or not seasonal

I have data set as shown. It is daily sales data for 4 different product for almost a year. I aggregated the sales of product for each day into . I plotted sales of 4 product as per date and got this ...
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1answer
27 views

How to use features in regression model with 2 of them in linear relation with the value to be predicted?

I am relative newbie to data science so please excuse me if its a trivial question. I have 6 features and want to predict the 'y'. These features are related to y in the training data-set as follows; (...
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0answers
15 views

Pricing transfer prices for oil hub? 390 Days of prices given

Need some input in how to attack this problem. Given are 8 timeseries: UK Oil price, Delivery Quarter 1 2020 UK Oil price, Delivery Quarter 2 2020 UK Oil price, Delivery Quarter 3 2020 UK Oil price, ...
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0answers
35 views

What is a good model for conditional data?

I am looking for statistical models of conditional data where some variables take certain values conditioned on values of other variables. For example, if $[x_1, x_2]$ are two variables defining a ...
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1answer
27 views

Comparing assault rates at one facility with two other facilities

Assaults on staff are fairly uncommon in our facilities with between 70-140 in a year at a given facility. Time, similar to 'person years' in epidemiology, is tracked as 'number of bed days' (i.e., ...
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41 views

Calibrating LASSO prior (how to select the scale hyperparameter)?

I want to use a LASSO prior (Laplace prior) for a location parameter $\mu$ $$\pi(\mu \mid s) = \dfrac{1}{2s}\exp\left(-\frac{\vert \mu \vert}{s}\right).$$ However, I do not know to calibrate this ...
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0answers
26 views

Strategies for predicting values of a time-dependent CDF, given covariates

I've got data that looks like this: ...