# All Questions

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### Forecasting Skew & Kurtosis

I have seen several models for estimating the expected value and variance of a distribution. I am curious, to learn if anyone has looked at models that extend beyond these first two moments ...
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### Two independent sample test one sided hypothesis test

Basic question: In a two independent sample test of differences in means, is it possible to have a one sided hypothesis? Typically, when you have 2 groups the two sample test only tests whether the ...
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### technical issues regarding to cluster analysis

Hi I would like to seek help with my cluster analysis using SAS. The main objective of the task is to segment customers into groups based on their similarity. The dataset contain mixed types of ...
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### How are individual trees added together in boosted regression tree?

I'm reading Introduction to Statistical Learning (Hastie et al), in which they describe the Boosted Regression Tree algorithm as following. What I do not understand is Eq 8.10 and 8.11. What do ...
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### Fieller's Theorem Equation computation with R programming [on hold]

Given that this is a fairly common used theorem, I am hoping someone has already used the R programming Language and console to work with this equation. Having a limited understanding of the ...
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### Threshold on tanh or sigmoid in Convolutional neural network

I have read several papers on Convolutional Neural Nets but I am yet to come across any that has used thresholds on tanh or sigmoid to decide whether the neuron will fire or not. Obviously this works ...
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### A Conditional Probability Question

Assume we know $$p(w) \sim N(0, \Sigma)$$ $$p(e) \sim N(0, 0.01)$$ $$y=w^\intercal x$$ $$o = y + e$$ Where w/x/o/y/e are all vector How do we calculate the distribution of $$p(y|o,x)$$
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### Bayesian Time Series Analysis Source

Is anyone able to recommend a source that covers Bayesian time series analysis in Winbugs?
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### How do panel regression estimates differ from those obtained from multiple time series regressions?

I am trying to familiarise myself with panel regression techniques and I would like to know how the parameter estimates obtained from a panel regression model differ from those obtained from multiple ...
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### Dummy variables in multiple linear regression with SPSS

1) Is effect coding (as opposed to dummy coding) necessary/possible in logistic regression (as opposed to linear regression)? I think the answer to this is 'no' but I would be grateful for your ...
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### Scoring model/formula to rank based on accuracy of data sources

Let us say i have 5 different data sources. My aim is arrive a score to arrive the accuracy of this data sources. It is like below 1. Refer the section Data confidence calculation in ...
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### Coverage probability Poisson - R [on hold]

I am trying to figure out in R a graph that displays the coverage probability of the confidence intervals for a parameter of a Poisson. I am taking as benchmark paper Brown, Cai & Dasgupta (2003) ...
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### Using SVM Enron Spam Corpus for Advertising or Any spam Corpus [on hold]

This is a bit specific. I want to train a support vector machine or naive bayes classifier to spot advertisements in HTML so I can clean before LDA analysis. Only a few percentage points of bad data ...
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### Stata Margins tool

Does anyone know how Stata creates their margins dy/dx output? I am trying to recreate some Stata output in SAS. The results of a logit regression give a coefficient of 1.4921, and an odds ratio of ...
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### Size of parliament in Lottocracy? [on hold]

Assume you are living in a country with a population of 100 million people. In this country the members of the parliament are not selected by vote but by lot (see Lottocracy). How many members would ...
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### Order Statistic Moments, INID Gaussian, Equal Variance, Unequal Means

I've been playing with this for a couple hours now and would like to figure it out if there is a well known solution. I want to calculate the mean of the order statistical distribution of N INID ...
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### Problem with getting neural network learned to calculate XOR

I am learning about neural networks. I found a course on Coursera about machine learning https://www.coursera.org/course/ml . What I am trying to implement is a neural network to calculate logical ...
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### What does the varImp function in the caret package actually compute for a glmnet (elastic net) object

I am fitting an elastic net model with glmnet via the caret package with 189 predictors and a binomial criteria (a,b) ...
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### Model formulation of mixed models: from R (nlme and gamm) syntax to mathematical

I have finalized two types of models, a linear mixed effects model and a generalized additive model for my data set. I have read and understood how it works and how to choose which model would be the ...
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### Quality measure k-means implementation in R [on hold]

I used a couple of methods to find the optimal number of clusters in k-means. From some research I found that people quite often use quality measures to deal with this problem. As I'm working with ...
14 views

### BI as a Master thesis topic [on hold]

I'm wondering which topic to choose for my Master thesis. I want to focus on BI area. But which part? Should it be data quality management, data visualisation.. I believe these topics are covered ...
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### Two experiments with shared control, can I generalize?

I have run two experiments, let's say the control condition is A. The two treatment conditions are B and C. I determined that B < A on some variable, and that C > A on that same variable. These ...
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### Finding significant values in my tree-like distributed data

i have a question about my data. Let me first describe what i know about it. I know that the number of data points I have is large (200-1000) I know each data point value is greater or equal to 0 I ...
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### minimax property of sample mean

Suppose $X_1,X_2,\ldots,X_n$ are iid $\mathcal{N}(\mu,\sigma^2)$, where $\sigma$ is known, but $\mu$ is not. We wish to construct a confidence interval of length $L$ (given) for $\mu$. Is it true that ...
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### How to do ranking with scikit-learn random forest model

I have a training dataset that I've developed, that has the following format: ------------------------------ | User ID | Item | Label | ------------------------------ | 001 | umbrella | 0 ...
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### Is there a default parameter choice for the spike-and-slab prior?

In the spike-and-slab prior, one needs to specify $h_{0j} = P(\beta_j=0)$, which demonstrates our prior belief about how likely $\beta_j$ to be an important predictor. Is there a default choice for ...
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### Intraclass correlation and simulating data

I will apologize in advance for this somewhat messy problem. I am trying to take an ICC reported from a previously published manuscript and design a general simulation program. Let's say the ...
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### Probabilistic forcasting

My question relates to probabilistic forecasting. How does one actually go about computing a forecast? Lets say I have some data that can be modelled by a specific distribution, and the values of the ...
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### Estimate mean & standard deviation of set S if I know stats of an inner set and outer set

Suppose I have sets $S_1\subset S_2\subset S_3$. I have the size, mean, and standard deviation of $S_1$ and $S_3$ and want to estimate the mean and standard deviation of $S_2$, where I only know its ...
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### Calculate mean of several tetrachoric correlation coefficients

how do I calculate the mean of several tetrachoric correlation coefficients? Do I have to use Fisher's z transformation before? Thank you
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### MINST Image Classifier in R: NaNs produced

I'm teaching myself to do image classification in R. I came across a great bit of code that employs K-Means and SVM to perform image classification (the code is available on GitHub) Feature ...
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### Nate Silver's Election Prediction Model

Nate Silver has been quite successful at predicting the outcomes of U.S. elections in the past, something which is described in his book The Signal and the Noise. The book contains some descriptions ...
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### Logistic regression : non exclusive predictors

I am doing a logistic regression . My outcome is a categorical (yes/ no) pain after surgery. The predictors i wish to model for includes the type of anaesthesia , among other predictors. The problem ...

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