# All Questions

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### Problem with Mann-Whitney U test in scipy

I am trying to perform Mann-Whitney test on a real data set using scipy. I extracted an example where the problem occurs. It seems that the function tiecorrect returns negative value which is the ...
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### Generate mixture model from data with features

I want to build a mixture model from my data, but using features of my data to calculate each component in the model. The data: For each point I have 34 associated features. Each feature is a boolean ...
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### Draw a multinomial distribution from a Dirichlet distribution?

I have a very rough understanding of the Dirichlet distribution and already seen some visualizations of its pdf over the 2-simplex, i.e., $\alpha$ is a 3D vector. However, I still do not understand ...
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### Best way to examine mortality tables?

I have a set of tables containing mortality rates (hazard rates) and I want to see how well these values reflect the influence of the covariates (age, sex, issue year, etc.). I also have actual ...
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### Variance functions and transformations in linear mixed models, beginner questions

First post here. I'm pretty much a newbie both in statistics and using R, but nevertheless trying to fit a linear mixed model with the package nlme. My question is about transformations/variance ...
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### Number of inputs used by ARIMA model

Should be an easy question but Google failed me. When using ANN for series forecasting one often uses may variables. For instance the number of shoppers might be determined by the previous number of ...
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### Variance and asymmetry on relative frequency class distribution

I don't know how to resolve this (easy) exercise. I've calculated the first output. But I don't know if it's correct. Calculate arithmetic mean, variance (standard deviation^2), concentration and ...
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### positive residuals after standardizing predictors in gls using R

I am using generalized least square in R. The original data I have seems to be OK when fitted with gls (judging from the residual vs fitted value graph). However, since I want to compare across ...
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### Difference between identity and diagonal covariance matrices

thanks in advance for the help. Suppose I am training a linear model. What are the conceptual differences between using a diagonal covariance matrix and the identity? It is clear to me that the ...
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### Test for correlation between continuous and categorical variable [duplicate]

I am wanting to know what type of statistical test would need to be carried out to determine if there is a correlation between one categorical variable and one continuous variable.
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### High negative correlation between intercept and slope

I was trying to fit several mixed linear models, however for 2 (out of 4) I am getting quite strange results. The point is that I've collected data from two courses (a few students were the same in ...
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### Error of bounded mean estimation with quantization

I have a distribution whose mean $\theta \in [0,1]$. Given $n$ observations, I compute the sample mean (say $\hat{\theta}$) and quantize it to accuracy $\frac{1}{n}$ (basically I can use only ...
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### In Probabilistic Graphical Models, what does it mean that r.v. X influences r.v Y?

I wanted to pin down what the intuitive phrase: r.v. X influences r.v. Y as precisely and as rigorously as I could, and wanted to check if my interpretation was correct and complete with the ...
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### Calculating probability of full house and royal straight in R poker simulation [migrated]

Given a poker simulation in R using vectors for the denomination and class of playing card in a loop, how would one go about identifying a given hand containing a full house or a royal straight. I'm ...
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### Regressing out a variable?

What exactly does it mean to "regress out" a variable or quantity? This is something I hear about all the time, but it's strangely difficult to find a precise description online. Any pointers - ...
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### How do I filter insignificant modes from a kernel density estimation

How do I detect the number of significant modes in a set of data? I have a set of 1 dimensional data where the number of modes are unknown. I'm familiar with python and scikit learn so I use the ...
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### How do I solve problem 1. c) in the following link? (Marginal Probability) [on hold]

https://moodle.concordia.ca/moodle/pluginfile.php/1785520/mod_resource/content/1/Assignment%201.pdf It seems as if I need to find the mean of the marginal distribution table, but I do not know what ...
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### disadvantages of Neural network method

Hello Dear Researchers! I want to list the advantages and disadvantages of Neural network methods for classification or estimation purposes. I have already found the advantages of NN method in many ...
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### Interactions in regression [on hold]

Consider a multiple regression model with gender as one of the predictors. Suppose gender has no significant effect in this model. Is it possible that an interaction of gender with an independent ...
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### Are there any packages to calculate accuracy, precision, recall and f-measure achieved by a KNN-classifier in R language? [on hold]

I have been trying to find packages to find accuracy,recall, precision etc performance metrics for the KNN-classifier. The closest I could find was caret but it says the object in its parameters has ...
Let $X_1, ... , X_n$ be i.i.d random variables with pdf given by $$f(x;\theta) = \exp(-(x-\theta))I_{(\theta, \infty)}(x)$$ It is asked to find a sufficient statistics for $\theta$ and to verify ...