# All Questions

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### Performance comparsion study on real data in Matlab (machine learning)

I need to compare performance using 2-classes' classifier – LDA classifier and Exact Bayes in Matlab. I have to use this dataset – http://archive.ics.uci.edu/ml/datasets/Skin+Segmentation. Can anyone ...
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### Sum of squared errors

Why do we use SSE (the sum of squared errors) in calculations. Why do not we use the sum of errors? Could you explain please?
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### 3x2 design - data analysis ANOVA/MANOVA? How to add interaction in the model?

Discription of experiment I am researching "The effect of review valence and brand commitment on consumer's purchase intention" for my university thesis. I conducted a 3x2(no review/positive ...
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### Difference in AIC and BIC values between sem and lavaan packages in R

I ran the same SEM model in sem and lavaan. I got the same parameters and - generally - very close test values, with the exception of AIC and BIC which were immensely different between the two ...
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### How to extract long run and short run coefficients from ARDL (UECM) estimates?

I have estimated ARDL(UECM) in eviews but I dont know how to specify or extract the long run an short run estimates/coefficienst? what is the standard procedure to do so?
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### Interpreting Multivariate probit

How do you interpret the results of a multivariate probit regression? Is it interpreted the same way as OLS?
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### Movie recommendation problem

I have a set of data with features of movies and features of users and a third matrix with ratings of user for each movie. I have to build a recommendation system for new users. Can you help me with ...
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### Finding Percentage Point of a Normal Distribution

Good evening all, I am doing a self-study exercise, but have been quizzed by a part of the question on finding percentage points of a normal distribution. I fully understand the first part of the ...
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### Where is my mistake in the following example about Viterbi algorithm?

I am trying to learn Hidden Markov Model, Viterbi algorithm. Therefore I was looking for an example to study. I came across a simple example from the website below; ...
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### A case of understanding customer behavior

Suppose I have a big online company, and many of my customers churned (i.e. they were paying, and then stopped). My goal is to understand why each of them churned. First I identify the complete set ...
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### how to code a random intercept and slope in a mixed linear model and apply LAM in SAS

I m a PhD student in New Zealand. I need to determine the impact of lameness in milk yield of cows. I measured milk yield daily as well as I recorded the cows that were observed lame in any one day . ...
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### What is the code for cubic spline regression model in SAS

I ran an experiment that identified lame and non-lame cows every day for 325 days from a pool of 936 cows in one herd. At the same time, I collected data on various variables like milk volume, fat and ...
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### What kind of distribution is this via t-distribution

Suppose we repeat an experiment identically and independently 100 times. Each time we construct a 99% conﬁdence interval for $\mu$ via the t-distribution. Let X = the number of times the conﬁdence ...
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### Inference with only left-censored data

Suppose I have a data set that is only left-censored data, ex: <5, <5, <5, <10, <10, <10 A technique to handle left-censored data is the Kaplan Meier estimate, see page 5 of ...
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### Not sure I understand how R calculates the covariance

Please forgive this silly question, I'm fairly new to statistics. Consider this R code: ...
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### Does the estimated overdispersion parameter of Negative Binomial depend on mean

Negative Binomial distribution can be parameterized using mean, $\mu$, and overdispersion $\psi$, so that the variance of NB is $\mu + \frac{\mu^2}{\psi}$. We know there is no analytical solution for ...
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### JAGS meta-analysis

I'm using JAGS to run a meta-analysis and I've run into an issue. I have calculated log-response ratios and errors for about 177 studies, where studies fall into one of 8 groups. I'm interested in ...
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### Hierarchical Bayesian modeling of incidence rates

Kevin Murphy's book discusses a classical Hierarchical Bayesian problem (originally discussed in Johnson and Albert, 1999, p24): Suppose that we are trying to ...
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### Finding an equation with many variables to fit a set of data

I am writing a program which takes notes from a keyboard as the input, (just numbers, 1 to 88) and decides which notes are played by which hand. There are a lot of variables, for example, the position ...
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### How to subset alternatives in nested multinomial logistic regression?

I am trying to predict whether or not captains in a particular groundfish fishery choose to fish on any given day and what variables may influence that decision. Originally I had planned on using ...
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### SVM for unbalanced data

I want to attempt to use Support Vector Machines (SVMs) on my dataset. Before I attempt the problem though, I was warned that SVMs dont perform well on extremely unbalanced data. In my case, I can ...
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### Why we shouldn't be obsessed with unbiasedness

In my Bayesian statistics class, my professor makes the remark that we should not be obsessed with unbiased estimator. First: I understand this statement in the sense of trading biasedness for ...
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### Identifiability in linear regression

If we have a generative model: $X_2=X_1a_1+\varepsilon$, where $\varepsilon \sim \mathcal{N}(0,\sigma_2^2)$, do we have $X_1=X_2a_2+\varepsilon '$, where $\varepsilon \sim \mathcal{N}(0,\sigma_1^2)$ ...
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### What does the | in |Z| mean in mathematical expressions for distribution statistics

I am doing some self study on statistics and noticed that in the notes that I was using the $|Z|$ expression as attached in the photos below. I am confused with the "$|$" that is being used. The only ...
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### which test to use here to test the significance of overlap with respect to a control?

i'm not sure what statistical test to use to compare a scenario like this: I have a list of candidate regions A (560k regions) and I want to know if my candidate regions enrich for a particular set ...