# All Questions

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8 views

### 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?
• 11
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### 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 ...
• 101
10 views

### 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 ...
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 <...
• 1,758
1 vote
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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### 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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### 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 ...
• 101
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### 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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### 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 ...
• 143
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,...
1 vote
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. ...
1 vote
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-...
15 views

### 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 ...
• 433
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, ...
• 25
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### 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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### 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 ...
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 ...
• 253
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....
1 vote
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. ...
1 vote
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 ...
• 123
1 vote
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)...
• 3,402
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 ...
• 1
1 vote
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 ...
• 2,049
8 views

### 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 ...
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: ...
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 ...
• 225
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### 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, ...
• 1,758
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 ...
• 119
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• 111
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### 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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1 vote
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 ...
1 vote
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, ...
1 vote