# All Questions

137,825 questions
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### Marginal effect from two models with different dependent variables

This question is somehow related to this one and this one. I have two models with the same independent variables on the same dataset. Model1: Y1 = alpha0 + alpha1 X1 + alpha2 X2 + error1 Model2: ...
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### Array of Real Values

Array of real values (01,02,03,04,...10) such that value 1 would be repeated 5 times, value 2 would be repeated 6 times and rest would be repeated 7 times each. How i could this in R.
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### Regression for multinomial distribution (negative and positive correlation coefficients)

I have a dependent variable, which is a multinomial distribution resulting from positive and negative correlation coefficients. Those correlation coefficients represent the relationships between ...
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### Forecasting using MA(2) model when past 5 observations are known

So given an MA(2) model : Xt = Wt + Theta1 * Wt-1 + Theta2 * Wt-2 Where Wt is white noise. (Normally distributed) and Theta1 and theta2 were available. Say if X96,X97,...X100 of the series were given ...
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### longitudinal vs. cross-sectional vs. panel analyses

I would appreciate some help distinguishing between cross-sectional, longitudinal, and panel analyses. We surveyed people at T1 and surveyed these same people at T2 (four weeks later). At T1, we ...
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### Using sample() to split a dataset [on hold]

I'm looking to split the 150 observation iris dataset into a specific number of observations for train and test; 112 and 38 respectively. I've tried the following: iris[,1:4] <- scale(iris[,1:...
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### Alternatives/Reccomendations for Multiple Comparisons?

please bear with me. I'm trying to get preliminary data analysis results from data generated through simulations in order to test two algorithms (one is called 'DFS', the other is called 'circular) to ...
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### Why does unconfoundedness not hold if the covariates are affected by the treatment assignment?

I found a mention inside the Rubin-Imbens Causal Inference book that: Unconfoundedness is generally violated if X includes variables that are themselves affected by the treatment. For example, in ...
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### Bayesian update of a confidence interval

How does one update a confidence interval using Bayes rule? Say, for example, an experiment shows that the mean lies in [A, B] with 95% confidence. Later, a colleague says they ran a similar ...
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### Generating three random numbers from normal distribution using 3 independent uniform numbers

Each of the variables A,B,C follows a normal distribution with E(A)=E(B)=E(C)=1,V(A)=1,V(B)=2,V(C)=4. Correlation between A-B=0.2,B-C=0,AC=0.8. We are given three independent uniform (on[0,1]) random ...
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### The relation of eigenvalue and PCs in PCA

In R, I got the result of PCA and eigenvalues and vectors and three eigenvalues above 1 were checked. If so, is it valid data from PCA results to PC1 ~ 3? Here is my eigen values and vectors, ...
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### How does one evaluate a null hypothesis of an absolute value of a parameter?

Say I am evaluating a null hypothesis such that H0: |p| = 1 Ha: |p| < 1 And want to understand how this differs in implementation and evaluation from the test: H0: p = 1 Ha: p < 1 Is this ...
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### What does it mean when running ANCOVA with two moderators and one of the interactions is insignificant when ran together?

I am hypothesizing that there are two moderators in the relationship between IV and DV. I ran one ANCOVA with moderator A and the interaction between IV and moderator A is significant. Then I ran ...
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### Tools in Data Science [on hold]

I am a new one in Data Science and Machine Learning. I have some experience in Java, Python, SQL, Jupyter and most polular libraries like scikit-learn, numpy, pandas, tensorflow, keras. What tools ...
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### How to properly integrate data from multiple studies in a training/testing classification framework?

I currently have data from several studies, with each having different sample sizes and possibly different set-ups. There is a common binary variable of interest across all studies that I would like ...
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### Question about using Bayesian rule as a classification for continuous data set

Please note that my question is not about coding. I am now learning Bayesian classification and I think I understand it in a discrete case. I have trouble understanding it for multivariate continuous ...
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### Knn Classification on iris dataset

I'm following along https://rpubs.com/Drmadhu/IRISclassification to understand Knn classification. Here's the code I have: library(FNN) iris.sample<-sample.int(n=nrow(irisdat),size=floor(0.75*...
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### How to select a single updated centroid if multiple centroids are equidistant for a single group when running k-means/k-medoids?

I am trying to write my own k-means and k-medoids clustering algorithms. I understand the general idea: given k centroids, one continually updates the centroids ...
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### Popular stochastic model for behavior of staying at the same position?

I am looking for a popular stochastic model employed for a trajectory of a fish which tries to keep staying at the initial position against water pressure from time-varying directions. The trivial ...
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### How to interpret ROC curve?

I am currently doing a classification problem for classifying the functional class and non-functional class of peptidase cleavage site. The data on non-functional class (negative class) is highly ...
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### Why does sklearn.linear_model.enet_path give different results than glmnet_python?

The results alpha path from enet_path and the lambda path from ...
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### Eigenvalues as weighting factors for projection results on corresponding eigenvectors in PCA

In Novel PCA-based Color-to-gray Image Conversion, the authors "utilize the eigenvalues as weighting factors for projection results on corresponding eigenvectors", in order to project a $(R, G, B)$ ...
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### Back-Transformation for Ln(X+1) of zero rich data

I have seen and read several similar questions, but mine pertains specifically to zero rich data. I will be back transforming my data based on a first order Taylor series approximation. As outlined ...
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### SVM one class outlier/classifier with Matlab

I have several time series (a small sample is in the end of the question) and I am trying to find the outliers using SVM. I have used this to find the outliers ...
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### How I specify a covariate in Anova model (r)

I have the following model: model = aov(y ~ treatment + Age, data = dt) How I determine Age as a covariate (covariable) in r? ...
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### What is the discrete equivalent of a truncated normal? [on hold]

Let random variable X be distributed with a truncated normal with unspecified mean, unspecified variance, a(the lowest limit) = 0 and b some fixed natural number greater than 0. With the Y axis we ...
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### Probability of Pregnancy

I have a probability question, I am not sure how to make of it. Hope you can give me some guidance, math has never been my strong subject. Assuming the lady is 36 years old and is considered part ...
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### Chi-square based tests tending to zero for large sample sizes [duplicate]

I think I have some misconception about chi-square based tests such as Pearson's test or McNemar's test. The way the tests are defined, the test statistics produced by the formulas are not stable ...
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### Is every distribution factorizable by an MRF also factorizable via a Bayesian network? And vice versa?

This has probably been asked before, so if it has please provide a link to the original question and close this as a duplicate -- I was not able to find the original question myself. Question: Let'...
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### is there a way to find suitable ratio for “ratio” in Matchit package in R

I am using matchit package in R to find a control set for my treated units and I am testing the model with different ratio to get suitable control set. Is there a way to find suitable ratio and I will ...
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### Ranking website page performance with number of page requests and load time

I have no background in statistics, so I find myself confused by this simple problem. I'm not even sure which search terms to use. I have some website performance data. I have the number of times ...
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### How do I check my GAN implementation is correct?

I wrote a GAN implementation and I trained that to produce some sample images after training on a dataset. The images looked visually fine. Now I want to test my implementation on the CI and make ...
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### Question regarding Taleb's metaprobability of p-values

There has been a other question here regarding Taleb's article The Meta-Distribution of Standard P-Values. I have a somewhat different question, at the very end of the article Taleb claims that: • ...
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### Is there a simple way to conduct a significance test on the equality of coefficients from a logistic regression?

Elsewhere some have proposed a method for conducting a significance test on the equality of slope coefficients using the equation: $Z = \frac{\beta_1-\beta_2}{\sqrt{(SE\beta_1)^2+(SE\beta_2)^2}}$ ...
21 views

### Do OLS residuals tell us anything about the distribution of the error term?

I'd like some intuition on a question that has long confused me. Suppose we have a data-generating process $$y_i = x_i' \beta + \varepsilon_i$$ where $\mathbb{E}[\varepsilon_i] = 0$, \$\varepsilon_i ...
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### Why is the infinite-population perspective usually taken in sampling? What underlying bias/convergence implications are there?

In sampling literature and causal inference literature, there usually is a distinction made about how to view observed data. The first is usually to view some observed data as having come from a ...
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### Is it appropriate to use estimated marginal means when model estimates are not significant but data is unbalanced?

Is it appropriate to use estimated marginal means when estimates (either interaction or main effects) are not significant but the data is unbalanced? I've come across variations of this question on ...
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### GPU for fully-connected network?

I'm interested in neural networks from a general machine learning and pattern recognition perspective and not as much from the perspective of image processing or NLP data. If I want to train a neural ...
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### Examples of how to report results of a GLS

I am looking for some good examples in the primary literature where a GLS was used. I am pretty new to mixed modelling, and while I got it working, I am struggling at the write up stage. Google ...
4 views

### How I specify a covariate in Anova model (r) [on hold]

I have the following model: model = aov(y ~ treatment + Age, data = dt) How I specify Age as a covariate (covariable) in r? ...
10 views

### Linear and Non-Linear dimensionality reduction with missing variables

I'm trying to compare the two types of reduction by applying it to a list of ingredients for about 1000 sponge cakes. The ingredient lists do however have miss certain ingredients out for some cakes, ...
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### How to standardize data with low variance?

I have quarterly data of federal fund rate (test set), e.g.: ...