# All Questions

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### Validating the percent variance explained of principal components on out-of-sample data

I'm trying to ascertain whether the variance explained by a certain PCA on an out-of-sample dataset is not due to random chance. Suppose I have a dataset X with size n-x-p, and I run a PCA and obtain ...
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### How to reduce RMS error value in regression analysis & predictions - feature engineering, model selection

There's this dataset containing the metadata of Twitch's top 1,000 streamers of 2020. You can have the details here. I am currently participating in a challenge to predict the values for Followers ...
3 views

### How to calculate synchronized returns among two different stock market using DCC-GARCH?

I am working out with the thesis paper Cheang(2018) to calculate synchronised returns between two stocks from different markets. I am trying to code this in R. I am using rmgarch package and using <...
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### Calculating Convolution Only for a Certain Interval Using "conv()" in MATLAB

Below you can see the code for convolution of two continuous functions. There is a function called fx which I took as the square root of a Gaussian distribution. The convolution is calculated using 2 ...
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### Alternative definition of a sample?

From my little knowledge of statistics, a sample is a subset of a population. Now I am reading a textbook on mathematical statistics. In the introductory section of the chapter on sampling ...
11 views

### Interpret the following impulse response

Basically i am investigating the impact of monetary policy on agriculture per worker using semi-annual data by employing vecm.
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### Cost Benefit Simulations

I am interested in looking at something like this: https://cran.r-project.org/web/packages/heemod/vignettes/c_homogeneous.html Suppose there is an insurance company. The inaurance company processes ...
11 views

### Correlation between multiple groups of variables

Suppose you have dataset with 10 variables (e.g. var1, var2, var3, etc.) . If you wanted, you could calculate the correlation between each pair of these variables (i.e. 10 C 2 = 45). But does such an ...
11 views

### When calculating proportion, is the total that I'm using to calculate it also the sample size?

This probably has a very simple answer and I'm just overthinking it. I have a very large dataset (~30,000 individuals), that contains data on casualties seen at a wildlife rehabilitation hospital. I'm ...
5 views

### Understanding implications multiple Imputation

so Ive been studying multiple imputation and I dont quite get it. Suppose I have two variables Y and X with Y has some missing values and the missing mechanism is MAR. Suppose I use stochastic ...
14 views

### How do you interpret LASSO dummy coefficients?

Let's say I have the typical ANOVA where X has 3 categories and I one hot encode. I then have: Y = b1X1 + b2X2 + b3X3 b1, b2, and b3, are basically how much mean(Y | X) deviates from 0 (and if the ...
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### Brain tumour detection using CNN

I have a fairly basic mathematical and implementational understanding of ML algorithms and CNNs, and I am trying to think of an approach for this task: https://www.kaggle.com/c/rsna-miccai-brain-tumor-...
21 views

### Transfer learning for regression problems

I have trained a regression model with 7 features for a given problem. Now, I have another regression problem (quite similar to the previous one) where I have only 6 samples in hand, but with 3 more ...
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### Staggered Average and Standard Deviation of incomplete dataset

I have an AxBxC matrix of measurements, from which an arbitrarily-sized-and-distributed number of measurements have been deemed invalid and removed (i.e. that matrix contains a mostly random ...
19 views

### Analysis of Deviance in R returns a significant factor, but the mean of each group does not show any difference

We performed a 45s test with dogs and humans, we measured the distance between the dog and the human every 0.25seconds with GPS. The data for one subjects are in the following format: Subject_Id ...
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### Normalization of test data when performing PCA projection

To briefly explain what I've been working on, I have two datasets: one as a reference(larger) and another for validation. I performed the PCA analysis with my reference dataset to create the ...
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### Computing logistic regression on variables of different years?

I am very new to R and statistics in general, so it is likely I am adopting the wrong approach. I have a large dataframe made of binary, character and numeric variables with n observations per year. ...
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### Find the points that make the biggest impact on the correlation

I am reconciling two time series, $X_{1...n}$ and $Y_{1...n}$. They are supposed to have close to 100% correlation, but in reality often not. When that happens, I want to quickly find the points that ...
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### General advice - multicolinearity of features in classification by neural network

I'm new to Neural Networks, and in whole to Machine Learning, so excuse my lack of knowledge on this subject and please bear with me. I am trying to train a shallow network (2 hidden layers, 15 nodes ...
15 views

### Simulate autocorrelated variable based on data in R

I am trying to simulate data for a longitudinal multilevel model. Let's say I want to simulate 4 observations of random variable X for N persons - how would I do that assuming autocorrelation of X to ...
21 views

### Intuition for why LDA is a special case of naive Bayes

The naive Bayes classifier assumes the regressors to be mutually independent, while linear discriminant analysis (LDA) allows them to be correlated. James et al. "An Introduction to Statistical ...
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### What can I do to make Student-T priors in a brm Bayes model less tall? [closed]

What can I do to make Student-T priors in a brm Bayes model less tall? Particularly this is a linear model: $a+bx$ And my current priors are: ...
12 views

### Is there a way to estimate bias in aggregated data?

I have a data set with aggregated data of two study groups. Twenty response variables were recorded for each group and for each response variable, the group size, mean, median, and the 5 and 95 ...
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### measure the overall similarity between two vectors

I have two paired vectors which report the number of times each object was found in the two experiments (the count value could be 0 or greater (e.g. 5,10,1000, etc)). I want to compare them and get a ...
74 views

### How to choose the mean and std when using KFold cross validation?

With reference to this post on feature scaling, and many tutorials out there, it is mentioned how we should avoid data snooping by performing say, feature scaling on the train set, and then use the ...
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### Multicollinearity in regression kriging

I am doing regression kriging for a certain pollutant as a dependent variable, and for independent variables I'm using 4 variables that add to 100% for all observations. Because of this when I use ...
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### How to compute p-values for shrinkage estimates of partial correlation?

I am using the pcor.shrink function from the corpcor R package to compute the shrinkage estimates of partial correlation ...
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### Can a fixed effect panel regression model still have endogeneity e.g. from time-variant error in the explanatory variable?

When you formulate a fixed effects panel regression model for observed data using the within estimator in R package plm, can there still be endogeneity present if there is error in the explanatory ...
10 views

### calc percentage of array possibilities [closed]

2 possibilities : A1 . B1 . C1 A1 . B1 . C2 so how we calc each one percentage ?,
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### How Do I Obtain the P Value of a Nakagami with R [closed]

I will like to obtain the p-value of a lakagami distribution. Let say I have the following: ...
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### Expected value of random variable with indicator function [closed]

Let $Z_n =Z+W_n$ where $Z \sim N(0,1)$ and $W_n$ is a binary random variable taking $n^2$ with probability $1/n$ and $0$ otherwise. Then for $M<\infty$, \$E(|Z_n| 1 \{|Z_n|>M \}) \ge E(|Z +W_n|...