# All Questions

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### Two age variables in regression

I am performing an hierarchical regression. One of the binary factor variables is if someone is 65 or older (1) or if they are younger than 65 (0). However, I am also applying stratification for age (...
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### What is the advantage of sparsity?

In many problems the solution is sparse and the authors of methods usually present it as an advantage. How could one leverage the sparsity in general? Why is an advantage?
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### Why is my semivariance so high?

I am using variograms checking for spatial autocorrelation in a resiudal pattern produced by a GLMM-NB. In theory, the semivariance should be bounded between 0 and 1 (that´s what I think at least as I ...
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### Correlation between an independent continuous variable and a dependent variable that takes integer values

I have to find a correlation between a numerical continuous dependent variable and a dependent variable which is the 'Number of User's Actions'. As you can figure out this variable gets integer values....
5 views

### VAR model with different time period for each series

I am trying to fit a Vector Autoregression model to forecast GDP growth Rate. I have 2 series, monthly GDP growth rate and a monthly economic indicator. For the monthly GDP growth rate, the latest ...
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### Finding levels/subsets that will give certain labels with high probabilty

Assume some 1000 data-points of the following pattern X1 X2 Y 2 B 1 1 C 0 6 A 0 3 B 1 3 C 0 where $X_1 \in \{1, 2, 3, 4, 5, 6\}$, $X_2 \in \{A, B, C\}$ ...
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### Interpreting adfTest Results in R

I do have a problem interpreting the data set results I got when I ran a adfTest (fUnitRoots package) in R. The test results are: Title: Augmented Dickey-Fuller Test Test Results: ...
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### Which of these options are covariance matrices?

Suppose I have covariance matrices $X$ and $Y$. Which of these options are then also covariance matrices? $X+Y$ $X^2$ $XY$ I have a bit of trouble understanding what exactly is needed for ...
5 views

### Cross validation for obtaining maximum median SRC Vaue

My dataset is comprised of 5 types of image's sets along with their distortions scores (DMOS) .Let us call the types as Type1,...
16 views

### normalisation in k means clustering on percentages and other numerical variables

I have several variables to include in k-means, some of them are percentages (between 0-1) and some of them are numerical variables (positive values). I know normalisation is required when the ...
12 views

### Why does -2log-likelihood decrease when you add new variables?

Suppose I'm conducting a study with follow-up survey after N years. Now I want to determine potential risk factors for mortality. I use a model selection procedure and get a table in which the ...
4 views

### Model ratio in a one-way repeated measures ANOVA in R?

I've got a dataset with two measures in a group of people, before (pre) and after (post) an intervention. Second measure is always greater than first one. My assumption is that the initial value ...
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### Regression Table for College GPA [on hold]

Table 1 College GPA for Associate Degree Graduates at a college OLS Regression Coefficients. N=608 Independent Variables Model1 Model 2 Model 3 Model 4 HS GPA 0.204** 0....
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### Difference between particle filter (PF) and recurrent neural network (RNN) for time series

Both method are used to estimate time series from data. The question is, when should I use one method or other? Is any advantage to use one instead of the other? I know that in a PF there is a hidden ...
33 views

### Arithmetic minus geometric means and the coefficient of variation

This question inspires a further question: For a probability distribution supported on the positive half-line, is the difference between the arithmetic and geometric means bounded by some known ...
3 views

### RNA-seq: Controlling FDR in multiple contrasts

I'm working on a RNA-seq analysis project and I have come across a statistics problem. I have 3 groups and I need to look for differential expression for each pairwise comparison. Do I control the ...
6 views

### Power Analysis for 1-sample Longitudinal Observational Study

I need to calculate the minimum detectable effect given a known N and desired power. I have a CONTINUOUS EXPOSURE and continuous outcome, each measured twice (baseline + 1 follow-up). If possible, I ...
13 views

### clustering based on string variables?

I am working on a project and currently experimenting cluster analysis. The dataset is mainly string variables, and I think my biggest three challenges in the data cleaning phase are the following: ...
5 views

### Resources for Determining Value-Added by Parameter Sweeps

I am working on a project that aims to use Design of Experiments to improve our testing process. We are performing tests using a parameter sweeps of numerous input variables (40+). Each input variable ...