# All Questions

139,068 questions
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### What is a technical term for a model that takes as input the output of multiple other models?

I have 60+ models (could be basic if-else rules or complex neural networks) that describe population risk. Each of the models has at least one output (often more). What is the technical term for the ...
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### 300k observations, significant results but very low adjusted r-squared

The model I have for the regression is in accordance with literature. I have about 300k observations and 25 dependent variables. When I run OLS regression, the output shows a couple of significant ...
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### Monte Carlo Simulation using R: Problem with sorting and significance

I am trying to implement the following statistical test using Monte-Carlo simulation. This method is based on the following paper: https://journals.ametsoc.org/doi/full/10.1175/JCLI4217.1 Details: ...
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### Is Stratified K Fold CV Needed when Estimator implements Balanced Class Weight?

I am working on a classification task with an imbalanced dataset. I am using Sklearn's ensemble RandomForestClassifier and set its class weight to Balanced. My question is, when I then GridSearch it, ...
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### SVM in the classification layer of a Feedforward neural network

I want to use SVM in the classification layer of a 2 layer feedforward neural network. Need guidance from the community on how to approach this problem. This involves capturing the features from the ...
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### Generalized linear model problem: how do we estimate the parameter $\lambda$ from the Poisson distribution?

To begin with, I am going to show off the context from which the problem arises. Consider that we are concerned with counting the number of organisms of particular interest within some sample. One ...
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### Could someone explain these ACF and PACF plots for what I think is a lag1 series?

I am trying to get my head around simple time series analysis. I think this R code shows my confusion. ...
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### Transformer based decoding

Can the decoder in a transformer model be parallelized like the encoder? As far as I understand the encoder has all the tokens in the sequence to compute the self-attention scores. But for a decoder ...
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### FE and clustered standard errors for a panel with firms, industries and years

I have an unbalanced panel of firms, years and industries. (1) At the moment I am running a panel regression with years and industries FE. My understanding is that I am counting for any omitted ...
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### Using a time series analysis to explain an event

I have hourly data for sand dune temperature at various depths as well as air temperature from summer 2015 to winter 2019. I have the day on which we saw our study species (one species) for the first ...
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### Terminology: “L1 regularization” even if I'm using mean instead of sum? [duplicate]

In my loss function I'm using the mean of the log-cosh error between the predictions and targets, as well as an additional regularization term that scales as the mean of the absolute value of another ...
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### Variance vs Variation

So far both terms have always meant the same thing for me, however, I started wondering, do they mean the same thing? The first 3 principal components explain 80% of the variance. The first 3 ...
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### Can sampling from a truncation of a random variable, rather than the original variable be more Blackwell-informative?

Suppose you are interested in finding the mean of a random variable. You have some prior belief of it and before sampling 1 observation, you can decide whether to sample from the original random ...
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### How to get PC values for individual datapoints using the prcomp command for PCA in R-Studio [on hold]

I just started using R-studio so please excuse me if this question has a glaringly obvious answer. I have been trying to carry out a principal component analysis using prcomp. Although everything ...
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### econometrics f-test HELP [on hold]

`Hi, i am having problems with this econometrics question, urgent help is needed!!! the model of observations t=1,2 .....,T is given by: yt=B1+B2x2t+B3x3t+B4x4t+ut an investigator wants to test ...
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### Optimal pandas dataframe size for seasonal ARIMA predictions over multiple timeframes

For backstory, please see this related question: Q3: How many rows of data should I keep in my respective timeframe for accurate ARIMA modeling (using SARIMAX)? An example of the p,d,q's of a 1H ...
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### Interpreting dummy variable interaction terms

I am attempting to model monthly retail electricity sales. To account for both the effects of seasonality and weather, I created an interaction term by multiplying 12 monthly dummy variables by the ...
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### Generating nested models for order selection tests [on hold]

I have created a parametric additive model for the median house price (as the response) and with the number of tax forms (x1) and the number of healthcare facilities (x2) as my covariates. I should ...
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### How to interpret a high sensitivity and low specificity using svm classifier?

I want to have your opinion on the performance of my SVM classifier (k-fold cross validated): Classification of class1(n=45)/class2(n=86) Accuracy: 65.4% Sensitivity: 88.2% Specificity: 22.2% AUC:...
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### How to implement constraints in a neural network for a regression problem?

Let's say I have different sensors in an engine, and I make a neural net which predicts the engine's temperature given different operating conditions measured by the sensors. I happen to know the ...
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### Estimate the restricted Nested Logit with R [on hold]

I find it very difficult to estimate the model proposed in the post title; in particular: I have done the following code ...
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### Indentify subset of data that follow linear regression

I have a dataset that first NL points follow a linear model and the next Na points follow a log model. My problem is that I do not know the value of NL and I want to get it from the dataset. I am ...