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2 views

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 ...
1
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0answers
7 views

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 ...
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0answers
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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0answers
4 views

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 ...
1
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0answers
17 views

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 ...
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0answers
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.
-1
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0answers
9 views

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 ...
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0answers
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 ...
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0answers
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 ...
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0answers
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 ...
1
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1answer
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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0answers
15 views

relationship between expectation of a ratio of random variables and a ratio of expectation of random variables

I know that in general for random variables $X$ and a function $g$ $E[g(X)]\ne g[E(X)]$. I would like to know when the following holds $E\Big[\frac{cov(X,Y|Z)}{var(X|Z)}\Big] = \frac{E[cov(X,Y|Z)]}{E[...
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0answers
11 views

Utility functions in multinomial logit model (NLOGIT software)

NLOGIT software allow to edit the utility function for each alternative. Format looks like below, ;model U(alternative 1)=<utility function 1>=constant1+coefficientsvariables U(alternative 2)=&...
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0answers
11 views

How can I select 10 features from a data base that has 40 features with Ridge Classifier and 10-Cross-validation?

Hi I have a base with p=40 and n=11750, I want to build a model with Ridge classifier (because the objective is predictive if one person is going to be defaulter=0 o not defaulter=1) that select the ...
1
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1answer
20 views

Question on labels in machine-learning

Suppose that $X$ and $T$ are both random variables. Where $T$ is a label. I just want to ask is tha finding probabilities on the label $P(T=t)$ or conditional probabilities $P(X=x|T=t)$ meaningful or ...
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0answers
15 views

What variant of logistic regression is correct here?

Here is my setup: I have M=200 municipalities who all rank high in corruption For each municipality, I pick a random sample of ...
2
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1answer
17 views

Difference-in-differences - Binary data

I am working on an exercise using conversion rate data on a travel website. The conversion rate is defined as the number of users in a given time period that make a purchase. There are two groups, A ...
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2answers
36 views

Beginner: Understanding difference between pmf, conditional pmf and likelihood

I have a point of confusion regarding the three types functions. I have looked at some other posts here and blogs and scripts and YouTube videos. But I still don't get it. Let's look at the coin toss ...
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0answers
13 views

Supervised NN not learning [duplicate]

I wanted to create a supervised NN that recognises numbers on images from scratch, pretty ambitious project for someone like me. But when I test it with a simple XOr gate, it completely fails. It just ...
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0answers
7 views

Probability fruit basket problem dependent/independed [duplicate]

Suppose we have two healthy but curiously mixed boxes of fruit, with one box containing 8 apples and 4 grapefruit and the other containing 15 apples and 3 grapefruit. One of the boxes is selected at ...
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0answers
11 views

Expected Value of Coupon Collector Problem with Restricted Set Size [closed]

Given a set S of unique marbles (with s = |S|) and bags with m marbles in each bag, what is the expected number of bags that would need to be collected to have a subset containing at least 1 of each ...
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0answers
18 views

Understanding differences between binomial and multinomial models

I'm attempting to model how 2 predictor variables affect the relative proportions of 3 different categorical groups. I started off by running a binomial model for the proportion of each individual ...
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0answers
7 views

Heteroskedasticity: conditional or unconditional - a (critical?) distinction yet adjective ignored

In non-time series, regression models when we say "heteroskedasticity" we almost always refer to "conditional heteroskedasticity". For example, the Breusch-Pagan test is a test for ...
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0answers
11 views

Parameter 'C' cannot be optimized for 'nu-svr'? mlr3 with kernlab

I am trying to optimize an SVR model within the mlr3 ecosystem with the kernlab package and I am getting the following error: The parameter 'C' can only be set if the following condition is met 'type &...
1
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0answers
23 views

Why does the best fit model (lower AIC) yield higher p values than models with higher AIC? [closed]

Background: I am running a model selection in R that includes 1, 2, and 3-covariate models. Each model aims to determine the effect of environmental covariates in the occupancy of different species in ...
0
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1answer
18 views

How to fit two (positive and negative) logistic functions using the same independent variable

My binary dependent variable (pollinator presence) responds to the independent variable (air temperature). With increasing temperatures there is a logistic increase in probability of pollinator ...
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0answers
13 views

Mixed logit as a Generalized Linear Mixed Model

I wonder if the Mixed Logit model could be understood, stated, and estimated as a Generalized Linear Mixed Model. Mixed Logit Consider a standard discrete choice setting where individual $n \in \{1,......
1
vote
1answer
24 views

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-...
2
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1answer
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 ...
1
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0answers
7 views

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 ...
0
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0answers
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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0answers
6 views

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 ...
0
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1answer
12 views

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. ...
0
votes
1answer
42 views

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 ...
0
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0answers
10 views

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 ...
1
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0answers
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 ...
2
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0answers
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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0answers
16 views

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: ...
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0answers
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 ...
0
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0answers
24 views

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 ...
3
votes
2answers
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 ...
0
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0answers
10 views

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 ...
0
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0answers
12 views

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 ...
0
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0answers
6 views

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 ...
1
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0answers
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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0answers
9 views

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: ...
1
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0answers
21 views

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|...
1
vote
1answer
27 views

Can I run a linear regression with a categorial independent variable (treatment) and adjust for gender at the same time?

I'm doing a retrospective study where I want to analyze whether a certain treatment (surgery A vs. surgery B) has an effect on the health status after the surgery measured with different parameters (...
0
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0answers
6 views

question regarding exporting data from Seurat package [closed]

I want to extract gene expression data for each cell and I wonder which option in “slot” to use to get log normalised data? is it “data”, “scale.data”, or “counts”?. I’m confused and I really want to ...

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