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Calculate variance on not normal distributed groups

Is there a way to calculate if the variances of two groups are equal when one of the groups is not normal distributed?
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0 answers
9 views

Why would quartile plotted against percentile not be a straight line?

In the famous Dunning-Kruger paper perceived and actual scores are plotted, with quartile on the x axis and percentile on the y axis. The message is the perceived scores, and the actual scores are ...
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  • 101
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Replicating LDA and LDA with LASSO constraints in Matlab - how to calculate the objective function in LDA and how to code LASSO in Matlab?

I am trying to reproduce some examples from an article: DALASS: Variable selection in discriminant analysis via the LASSO from Trendafilov and Jolliffe (2007). I have two questions about two parts of ...
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3 votes
1 answer
73 views

Usefulness of KS tests and other similar distribution comparing tests

I am working on a machine learning binary classification problem. I have an outcome variable status called as loan paid and <...
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1 vote
0 answers
26 views

How to statistically compare two numerical maps? [closed]

I have spatial temperature data on a relative scale from 1 to 0 on several days. The data sets have the same resolution, origin, and extent. How can I statistically compare them? How to identify ...
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-1 votes
0 answers
9 views

Chi square interpretation [closed]

Hello what does u value mean in this table, what does it indicate? This is Mann Whitney test
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0 answers
15 views

R squared of subgroups

I am trying to predict a value using a linear regression, and I get an R squared of 0.63. My data is composed of 5 different groups (each with different ...
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  • 101
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0 answers
10 views

How to obtain residuals of ADF test in R? [closed]

I was running an ADF test for normality in R and want to check whether residuals are corelated or not. How to extract the residuals of the ADF test in R?
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0 answers
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Distribution of true value when measurement imprecision is non-constant

What I believe to have understood so far (I am not a mathematician or a statistician, so please correct me if I'm wrong.) Say we are making measurements of some phenomenon $X$, and we have a normally ...
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2 answers
26 views

About the Numbers of Dummy Variables

I have a question on the choice of dummies in categorical regression. If there are 4 categories, can I just choose 2 dummy variables to represent them in the following way: Category-Z1,Z2 c1-1,0 c2-0,...
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1 vote
0 answers
31 views

How to determine how much variation was due to the differences between a group?

I am working on the data set that consists of Patients (after stroke), Time (then can walk after a going through the program), and Program they follow. ...
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1 vote
1 answer
25 views

When does a difference in means not capture the true treatment effects vs a regression with pre-treatment controls?

A question from Gelman - Regression & Other Stories... In answer to my own question...my understanding is that a difference in means should not capture the treatment effect when there are pre-...
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Should we care about correlations between model performances while we search for the best model?

When we fit (train) a regression model, we usually pick the best performing model (for example the one which gives the smallest RMSE). By doing this we do not take into account the correlation between ...
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2 votes
1 answer
24 views

upper confidence interval limit are NA for median overall survival

I have survival data set and had issue of getting upper 95 % confidence interval for median overall survival. I had observed other users had similar issue and I went through all suggestion. However, ...
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0 answers
15 views

Dependent variable standardization in neural networks

I am using a multilayer perceptron model to predict urban temperatures. I have standardized the independent variables before training the model. However, I have not standardized the dependent variable....
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0 answers
6 views

Are stacked meta models for time series forecasting still considered forecasters?

I am working on building a meta model that is based on the principle of stacked generalisation (1). In a nutshell, this method works by using building a meta model based on the predictions of various ...
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0 answers
9 views

Find fisher information matrix for optimization estimator

I have that $$f(x)=\frac{1}{\sqrt{2 \pi}}e^{-\frac{1}{2}x^2}$$ I have the conditional distribution: $f_{\beta}(y|x)=\frac{1}{\sqrt{2 \pi}}e^{-\frac{1}{2}(y-\beta_0-\beta_1x-\beta_2x^2)^2}$ and we have ...
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  • 253
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0 answers
19 views

Can a kernel be constructed from any arbitrary bivariate function?

For a kernel $\kappa(x_i, x_j)$ to be considered valid, it must be symmetric and have a positive semidefinite gram matrix for any set of points $\{x_1,...,x_n\}$ (ref: page 4 of http://www.cs.berkeley....
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1 vote
0 answers
34 views

Significance test for comparing different 10-fold cross-validated Machine Learning Regressions

Is there a recommended significance test for comparing different 10-fold cross validated regressions? For instance, I want to compare the performance of LASSO against Random Forest for my dataset. ...
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1 vote
0 answers
22 views

If there is a high correlation between two variables, should we expect the high linear regression coefficient?

I have a data set with multiple features, let suppose $x_1,x_2,x_3,x_4$ and my dependent variable is $y$, when I compute the correlation matrix for $y,x_1,x_2,x_3,x_4$ then imagine the correlation ...
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1 vote
1 answer
25 views

Is there a standard error of the mean for when population size is known?

Background Let us suppose that we are sampling from a finite population which is itself drawn from a univariate normal distribution. This accomplishes (1) having an underlying probability model and (2)...
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0 answers
14 views

eigenvector terminology [duplicate]

This is a basic question about PCA. The term eigenvector seems to be used in different scenarios and I would like some help improving the precision with which I use it. It is used for the unit ...
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  • 1
1 vote
0 answers
8 views

Efficient storage of functional data

I have access to a sample (size $N$) of functional data. Each observation corresponds to $C$ functions. Each function $f_{n,c}$ is represented by $T_n$ points for $1\geq n \geq N, 1\geq c \geq C$. All ...
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Type of Hypothesis Test Question

I’m trying to answer if males or females rate “The Office” higher or not. Initially, I was planning on using an independent samples t-test, but I wasn’t sure if that was appropriate since nearly three ...
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7 views

What is the appropriate type for the variables to be included in CART models?

I am building a CART model. However, I have certain doubts about the type of the explanatory variables to be included in the model. I ask you for your help and advice on these two specific questions: ...
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0 votes
1 answer
20 views

Mean centering and average marginal effects

I was reading Wooldridge's "Introductory Econometrics," in which he said: "The centering of explanatory variables about their sample averages before creating quadratics or interactions ...
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  • 225
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0 answers
11 views

Why PR score is down when balanced accuracy is good?

I just read this discussion here and here. I have a dataset of 977 records where class proportion is 77:23. My balanced accuracy is 75.5, ...
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  • 1,758
0 votes
0 answers
3 views

How to prepare constructs for inputting in a deicion tree from likert scale items

I have to use 5 variables in my decision tree as predictor variables. Each variable is an average score of Likert scale items as follows: Self-control is a construct of 10 variables. Each of these 10 ...
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0 answers
6 views

Assumptions for correlation disattenuation

I am familiar with the Spearman disattenuation formula for two random variables $X^\prime$ and $Y^\prime$ measured as $X$ and $Y$ with measured correlation $r_{xy}$ and reliabilities $r_{xx}$ and $r_{...
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0 answers
11 views

How to have a constant error[b-a] for a range of values [1d array] in decending order that are not linear but are semi-linear?

I am trying to generate n numbers in decending order (for the purpose of decreasing order of weights) such that their sum should be 100 and more importantly the difference between anytwo numbers ...
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  • 1
1 vote
1 answer
22 views

Calculating sampling variance in multilevel meta-analysis

I'd like to conduct a three-level meta-analysis using R. I see that several papers recommend calculating the level 1 sampling variance using Cheung's 2014 formula 14. However, I'm wondering if it is ...
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0 answers
42 views

How can I get the Binary Cross Entropy from the Cross Entropy function for GANs

I got the definition of log-likelihood by Goodfellow's Deep Learning book: \begin{equation} \label{eq:loglikelihood} \theta_{ML} = {argmax}\sum_{i=1}^{m} \log p_{model}(x_i; \theta). \end{...
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0 votes
1 answer
13 views

Error Terms in the ANOVA Summary Table

my lecturers require us to write the error term for the effect/source in the ANOVA summary table. Such as below: I don't understand how to find which S(error) term goes to which source. And I do know ...
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  • 1
1 vote
1 answer
23 views

Stata teffects ATET

How does stata estimates ATET (Average Treatment Effect on the Treated) using teffects psmatch. I understand the average treatment effect (ATE) is computed by taking the average of the difference ...
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0 votes
0 answers
14 views

Estimated lognormal PDF shifted compared to data

I have experimental data (~100k observations) that appear to be from a lognormal distribution. I am attempting to estimate the distribution parameters using ...
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2 votes
2 answers
36 views

How is AUC helpful when we only need one threshold of a classifier

AUC is a summation of performance at different thresholds, but do we only care about a good performance at one threshold? Imagine a classifier with a low ROC but shots up at point of a low FP and high ...
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  • 21
0 votes
1 answer
15 views

Bayesian model comparison with systematic error

Two parameters $(x,y)$ were measured for 3 different objects, wielding the following results: $$\{ (x,y) \}= \{ (1,3), (3,5), (5,9) \}$$ Knowing that the error in the estimation of the values $y$ is ...
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  • 109
1 vote
0 answers
14 views

After using inverse probability weight, two groups are still significant

I used the inverse probability weight to eliminate the bias of demographics. After creating the propensity weight, I conducted series chi-square tests to compare demographic variables among treatment ...
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0 votes
1 answer
38 views

How to prove that $e^{−7X}$ is a random variable, given that $X$ is a random variable

How to prove that $e^{−7X}$ is a random variable, given that $X$ is a random variable. Additionally, ¿can you provide a bibliography to learn more on this topic?. I also wanna know the proof that $ln(...
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1 vote
0 answers
14 views

Can the F test be generalized for a null hyp where variances are unequal?

Sorry for the question, maybe this appears in a book a little more advanced than the ones I have seen. Suppose we have two samples from normal distributions with sample variances $S_{n,1}^2$ and $S_{m,...
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  • 179
1 vote
1 answer
27 views

Anova shows a main effect but not the t-test

I run an ANOVA which indicates that a variable is significant, but running a t-test on the same variable shows no significance. Is this a consistent result ? Here are more details of what I did: My ...
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0 votes
0 answers
6 views

Group by in stata [closed]

Given an existing table that contains a list of observations: colA, colB, value 0, 0, 11 0, 0, 12 0, 1, 11 0, 1, 22 1, 1, 33 How do I ...
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0 votes
0 answers
11 views

Apply Shrinkage Coefficient to Exponentially Weighted Moving Covariance Matrices

Title says it all. I'm working on doing volatility forecasting and like the approach of exponentially weighted moving covariance matrices, but I also know that applying shrinkage coefficients further ...
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1 vote
1 answer
21 views

Adding/removing covariates in lmer?

I am trying to add covariates in lmer, but I do have difficulty with figuring that that, can anyone help me out with this? I have this happy_plot = lmer(happy_score ~ life_quality +(1|subject), data) ...
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1 vote
0 answers
17 views

Binary regressor - what happens if people move from one category to the other?

Suppose I have the following regression model: Monthly alcohol consumed A as independent variable, regressed on a binary regressor S (S = 1 if smoker, S = 1 if non-smoker), and through OLS I get an ...
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1 vote
0 answers
19 views

When does the Instrumental Variable (IV) method fail?

Consider the following ARMAX model: $$ y[k]=\alpha y[k-1]+\beta u[k-1]+e[k]-0.7e[k-1] $$ where $e[k]$ is a white noise. One can see that $e[k]-0.7e[k-1]$ is a filtered noise and thus using ordinary ...
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  • 111
2 votes
0 answers
14 views

lme4: glmer() warning messages with count data mixed-effects model and how to proceed with model fit

I have fitted a GLMM with the function glmer of lme4 package. My data consists of a repeated measures count variable, which I am trying to explain with a continuous variable (week) and some ...
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  • 21
1 vote
0 answers
10 views

Predicting Value in multi-dimension data

I need help with my data, I mix 2 different powder materials to get one powder with a specific quality number. So, this resulted in quality numbers depending on 4 features, the quality of materials 1 ...
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1 vote
0 answers
10 views

Synthesis without meta-analysis, z-score for 2 proportions?

I am doing a meta-analysis. One of the outcomes I meta-analyzed involved pooling multiple types of related complications. There wasn't enough data to pool the individual reasons for the complications, ...
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1 vote
2 answers
38 views

Which metric to use for language translation?

So I am using a pre-trained model to do the language translation Eg: Input = "Good morning" Output = "Bonjour" I would like to see if the ...
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