# All Questions

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### Empirical distribution of regression coefficient

I have understood the following R codes . But I have not understood What is the message (summary) of the codes? ...
2 views

### What is the point of graphical models?

I spent the day learning about the bnlearn package in R only to discover that Bayesian models do not work with undirected graphs. I'm trying to learn about the Markov Random Field Network, and so far ...
3 views

### Orthogonal polynomials contrasts for regression (unbalanced)

We can obtain the sum of squares of a contrast for a regression of degree $j$ by: $$SSR_j=\frac{\left(\displaystyle\sum_{i=1}^{I} C_{ji}T_i\right)^2}{rK_j},$$ where $I$ is the number of levels of ...
8 views

### Sampling, feature selection and preprocessing in cross validation

To brief my question, I want to clarify the order of parameter tuning and the correctness of the flow in my scheme. In my classification scheme, there are several steps including: SMOTE (Synthetic ...
24 views

### Probabilities vs. Odds Ratios

Suppose we know that the probability of a female getting into a program are $p=.7$ and $q=1-.7=.3$ for males. Then we know: $$\mbox{odds}(\mbox{female}) = .7/.3 = 2.33333$$ ...
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### meaning of partial correlation in regression with no significant association

When I have a simple multivariate regression with two independent variables $$y = \alpha_0 + \beta_1 X_1 + \beta_2 X_2 + \epsilon$$ and I want to compute the partial correlation squared ($pr^2$) of ...
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### Given a data table with outlier data points, how to determine whether the data table include global outliers or local outliers?

As we know, outliers are categorized into (i) global outliers and (ii) local outliers. There are many algorithms for detecting global outliers or local outliers. My question is: given a data table ...
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### How to perform a regression analysis on repeated measure data

I have two sets of data: A set of 100 observational variables for 10 subjects measured at three different time points Two performance variables for the same 10 subjects measured at the same three ...
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### Why do I get completely different Effect Sizes using same data but different methods?

When I calculate Effect Sizes (Cohen's d) on the same study using different methods I get completely different effect sizes. For example: (t=4.81, P<0.001, d=0.41) I also calculated d=0.41 using ...
18 views

### Intuitive explanation of the F-statistic formula?

Introduction to Statistical Learning defines the F statistic as follows: (TSS - RSS) / p over RSS / (n - p - 1) I am trying to interpret this formula intuitively - the numerator looks like the ESS ...
9 views

### What is the meaning of significant in statistics? [on hold]

I got a list of glossary terms which I have to find comprehensive definitions for. The last one is significant. What does significant mean in statistics?
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### Comparing two sets of equal width binned data

I have two distinct sets of ~1500 intervals of differing lengths - let’s call them Interval Set 1 and Interval Set2. I have ...
23 views

### Why time series analysis is not considered a machine learning algorithm

Why is time series analysis not considered a machine learning algorithm ( unlike linear regression). Both regression and time series analysis are forecasting methods. So why is one of them considered ...
13 views

### Modelling parameters in maximum likelihood

Often times I'll write down an idea and have no idea if (1) It's a good idea, and (2) If it is a good idea, how much has it been applied / studied. I'm asking this question in hopes to get insight on ...
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### Are the total false positives and false negatives of a large confusion matrix equal?

I have a confusion matrix which is 20x20 that is the product of a random forest classification of ~20k instances. Each of these instances was put into a specific class where rows are actual class and ...
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### The difference between adding a main effect of Factor C, and also adding an interaction between Factor A and C into a regression model?

I have a logistic regression model with two dichotomous predictors: Factor A and Factor B. I found that there is a significant main effect of both Factor A and Factor B. Now suppose I want to see if ...
4 views

### Dynamic Panel data analysis

Can anyone please explain the intuition and interpretation of Arellano-Bover/Blundell-Bond models also called System GMM?
9 views

### How can I combine two variables into one in order to obtain an overall response frequency?

I'm a graduate student learning R and I'm struggling to figure out how to create a sum of the # of respondents who selected a particular response for a total scale. For example: The scale is made up ...
7 views

### R - Interpreting neural networks plot

I know there are similar question on stats.SE, but I didn't find one that fulfills my request; please, before mark the question as a duplicate, ping me in the comment. I run a neural network based on ...
4 views

### Goodness of fit test for binned multi-sample data

Let's say I have two samples and 5 bins. In each bin, I have a (positive) value and a measurement error on that value for each of the two samples. The value and corresponding measurement error ...
20 views

### Using Markov Chain Monte Carlo to compute the chances that a particular solitaire laid out with 52 cards would come out successfully

Based on some references I got from another question I learned that: While convalescing from an illness in 1946, Stan Ulam was playing solitaire. It, then, occurred to him to try to compute the ...
6 views

### How to readibly visualize four related streams of network data?

I have network data coming from four different data streams simultaneously, and would like to visualize the data on some sort of concurrent timeline so I can identify potentially related events. I ...
23 views

### Bootstrapping a t-test in R

I have two groups of individuals (22 in each group), which I compared using a t-test. The difference between groups was non-significant (p = .17). Because the p-value was quite low, my supervisor ...
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### General definition for higher order co-moment matrix

Is there a general equation or procedure for computing higher-order co-moment matrices (i.e., coskewness matrix, cokurtosis matrix, etc) for a vector of random variables? For example, the covariance ...
13 views

### Independence between sibling groups?

I am a novice at statistics and I would sincerely appreciate your help with my question: I am working with a control group and 2 sibling groups and have a mixed design (i.e., one withing group ...
11 views

### Choosing the most suitable similarity metric [on hold]

Which of the following is the most suitable for calculating similarity between texts about 145 character long? Damerau-Levenshtein distance Levenshtein edit distance Sorensen-Dice coefficient ...
15 views

### Applying Rubin's rule for combining multiply imputed datasets

I am hoping to pool the results of a pretty basic set of analysis performed on a multiply imputed data (e.g. multiple regression, ANOVA). Multiple imputation and the analyses have been completed in ...
18 views

### optimizing over a set of symmetric matrices

I need to minimize a complicated loss function, $f\left(\Lambda\right)$ over a set of symmetric matrices, $S_{p}$ of dimension p, such that all the eigenvalues of $\Lambda \in \left[0,1\right]$. I ...
15 views

### Are any discussion here dedicated to data visualization? [on hold]

Is there a directory of data visualization resources similar to this one? http://www.data-visualization.org/
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### Difference in Difference method: how to test for assumption of common trend between treatment and control group?

Following a comment from a previous thread, I want to know how one can test for the assumption of common trend between the treatment and control group in the Difference in Difference method? Can I ...
11 views

### Unsupervised Anomaly Detection with Mixed Numeric and Categorical Data

I am working on a data analysis project over the summer. The main goal is to use some access logging data in the hospital about user accessing patient information and try to detect abnormal accessing ...
17 views

### Age rounded down. Ordinal or Ratio?

Usually age is rounded down (i.e $15.7\simeq 15$). So shouldn't we treat it as an ordinal and not a ratio scale variable? If this is a duplicate question, please refer me to the duplicated question.
177 views

### How does quantile regression “work”?

I am hoping to get an intuitive, accessible explanation of quantile regression. Let's say I have a simple dataset of outcome $Y$, and predictors $X_1, X_2$. If, for example, I run a quantile ...
7 views

### Using partial AUC as Caret metric for cross-validation?

I'm evaluating a grid of tuning parameters using Caret with metric="ROC" for cross-validation. Is there any simple way to use as metric the area under the curve for an specified interval of the ROC ...
8 views

### Comparison of distribution of two datasets

How do I compare distributions of two datasets with discrete distribution? Two-sample KS test only works for continuous (I was able to find implementation of one-sample KS test that works for discrete ...
32 views

### Analyzing seasonality in data

In order to analyze the data in presence of seasonality, I used two methods: Proportional hazard model (Cox model) and time series method (Triple Exponential Smoothing (Holt Winters Method)). Now , my ...
16 views

### Convergence in distribution [on hold]

Say I have n boxes and m balls. The balls have distribution of colours given by F. The size of the boxes varies with distribution G. Each box has t balls and the number of balls is given by the ...
6 views

### Problem applying a weight to the nlme() function [migrated]

First time poster here. I am currently attempting to fit a nonlinear mixed-effect model to predict the crown ratio of a tree using the nlme() function from the ...
15 views

### Can I use Principal Component Regression/Analysis to identify Raman peaks in varying concentrations?

I have data of varying concentrations of a particular substance in water. I recorded its Raman signals between 1 ppt to 1 ppb using identical parameters. I would be using Savitzky-Golay filtering to ...
23 views

### How I can get best arima model in R? [on hold]

I would like to build a time series model for univaraite data in order to predict or forcast. I am a bit new to R but know some of the syntax. More over, I would like to get the best arima model with ...
9 views

### Prediction of one time series from another with multi-dimensional predictors

I have the following problem (I am a newbie to the field so my apologies if this is something standard). I have two time-series with the same (categorical) predictors (x1,...,xn), n is approximately ...
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### Two way Friedman ANOVA in R

I have ranked concentrations (from 0 to 5) of 5 different proteins from 3 different locations from the same patient. In total, 15 measures per patient and 61 patients, so 915 observations. What I'd ...
52 views

### $E[\log(X)]$ when $X$ follows binomial

I am looking for solution and some references for the following expectations: $E[\log(X)]$ when $X$ follows binomial with parameters $n$ and $p$, i.e. $E(X)=np$ $E[\log(a+bX)]$ where ...
9 views

### Correct formula for unbiased estimate of population covariance [duplicate]

Is this formula a correct way to estimate population covariance from a sample? $$s_{xy} = \frac{1}{n-1}\sum\limits_{i=1}^{n}(x_i-\bar{x})(y_i-\bar{y})$$
10 views

### How can I use negative binomial regression with caret?

I'd like to use negative binomial regression with caret. However in the list of supported models I can't find it. I tried to use: ...
13 views

### Statistics for Survey/Research: N subjects, 4 Rational Numbers, 16 Yes/No questions

I am conducting a survey/test on different people. Let's say I have N subjects I administer them a test with two parts which they are scored as pass or fail (1 or 0) Then I ask them some ...
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### How can 1 more feature disrupt a Random Forest's confusion matrix?

I'm trying to predict a binary variable with both random forests and logistic regression. I've got imbalanced classes (approx 1.5% of Y=1), so i'm calling ...
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### Multiinformation (aka Total Correlation) based feature vector selection

I would be happy to discuss the question with an information theory specialist. It is not exactly about the Mutual Information. I use a multiinformation metric (available, for example, in R's ...
20 views

### Coefficient of Determination with Multiple Dependent Variables

I have X | Y1 | Y2 data, that I fit with some model. The model produces two values for one independent variable, where one is compared with the Y1 values, and the ...
9 views

### non parametric analysis of variance in small, unbalanced data set

I'm facing a data set composed of five different dependent (1,2,3,4,5) and three independent (I,II,III) variables. 1,2,3,4,5 are continuous but not normally distributed. I,II,III are qualitative, I ...

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