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1500 questions
39
votes
1 answer
Why is Mantel's test preferred over Moran's I?
Mantel's test is widely used in biological studies to
examine the correlation between the spatial distribution of animals (position in space) with, for example, their genetic relatedness, rate of aggression or some other attribute. Plenty of good…

Ladislav Naďo
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39
votes
4 answers
ANOVA on binomial data
I am analyzing an experimental data set. The data consists of a paired vector of treatment type and a binomial outcome:
Treatment Outcome
A 1
B 0
C 0
D 1
A 0
...
In the outcome column, 1…

speciousfool
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39
votes
1 answer
Link Anomaly Detection in Temporal Network
I came across this paper that uses link anomaly detection to predict trending topics, and I found it incredibly intriguing: The paper is "Discovering Emerging Topics in Social Streams via Link Anomaly Detection".
I would love to replicate it on a…

Olga Mu
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39
votes
6 answers
Are neural networks better than SVMs?
For some time now I have been studying both support vector machines and neural networks and I understand the logic behind each of these techniques. Very briefly described:
In a support vector machine, using the kernel-trick, you "send" the data…

Alberto Cindario
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39
votes
2 answers
Which search range for determining SVM optimal C and gamma parameters?
I am using SVM for classification and I am trying to determine the optimal parameters for linear and RBF kernels. For the linear kernel I use cross-validated parameter selection to determine C and for the RBF kernel I use grid search to determine C…

Kywia
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39
votes
8 answers
Graphical data overview (summary) function in R
I'm sure I've come across a function like this in an R package before, but after extensive Googling I can't seem to find it anywhere. The function I'm thinking of produced a graphical summary for a variable given to it, producing output with some…

robintw
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39
votes
1 answer
What are easy to interpret, goodness of fit measures for linear mixed effects models?
I am currently using the R package lme4.
I am using a linear mixed effects models with random effects:
library(lme4)
mod1 <- lmer(r1 ~ (1 | site), data = sample_set) #Only random effects
mod2 <- lmer(r1 ~ p1 + (1 | site), data = sample_set) #One…

mjburns
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39
votes
3 answers
Brain-teaser: What is the expected length of an iid sequence that is monotonically increasing when drawn from a uniform [0,1] distribution?
This is an interview question for a quantitative analyst position, reported here. Suppose we are drawing from a uniform $[0,1]$ distribution and the draws are iid, what is the expected length of a monotonically increasing distribution? I.e., we…

Amazonian
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39
votes
2 answers
Can somebody explain to me NUTS in english?
My understanding of the algorithm is the following:
No U-Turn Sampler (NUTS) is a Hamiltonian Monte Carlo Method. This means that it is not a Markov Chain method and thus, this algorithm avoids the random walk part, which is often deemed as…

user3007270
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39
votes
3 answers
Interpreting residual diagnostic plots for glm models?
I am looking for guidelines on how to interpret residual plots of glm models. Especially poisson, negative binomial, binomial models. What can we expect from these plots when the models are "correct"? (for example, we expect the variance to grow…

Tal Galili
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39
votes
2 answers
Why is mean squared error the cross-entropy between the empirical distribution and a Gaussian model?
In 5.5, Deep Learning (by Ian Goodfellow, Yoshua Bengio and Aaron Courville), it states that
Any loss consisting of a negative log-likelihood is a cross-entropy between the empirical distribution defined by the training set and the probability…

Mufei Li
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39
votes
3 answers
How to take derivative of multivariate normal density?
Say I have multivariate normal $N(\mu, \Sigma)$ density. I want to get the second (partial) derivative w.r.t. $\mu$. Not sure how to take derivative of a matrix.
Wiki says take the derivative element by element inside the matrix.
I am working…

user1061210
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39
votes
6 answers
What is difference between “in-sample” and “out-of-sample” forecasts?
I don't understand what exactly is the difference between "in-sample" and "out of sample" prediction?
An in-sample forecast utilizes a subset of the available data to forecast values outside of the estimation period. An out of sample forecast…

Engin YILMAZ
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39
votes
6 answers
How did scientists figure out the shape of the normal distribution probability density function?
This is probably an amateur question, but I am interested in how did the scientists come up with the shape of the normal distribution probability density function? Basically what bugs me is that for someone it would perhaps be more intuitive that…

bonehead
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39
votes
7 answers
Can deep neural network approximate multiplication function without normalization?
Let say we want to do regression for simple f = x * y using standart deep neural network.
I remember that there are reseraches that tells that NN with one hiden layer can apoximate any function, but I have tried and without normalization NN was…

Brans Ds
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