0
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0answers
2 views

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 ...
0
votes
0answers
5 views

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 ...
0
votes
0answers
5 views

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 ...
0
votes
0answers
10 views

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 ...
0
votes
0answers
7 views

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 ...
0
votes
0answers
7 views

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 ...
0
votes
0answers
5 views

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 $$p(y|o,x)$$
0
votes
0answers
8 views

Bayesian Time Series Analysis Source

Is anyone able to recommend a source that covers Bayesian time series analysis in Winbugs?
0
votes
0answers
12 views

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 ...
0
votes
0answers
6 views

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 ...
0
votes
0answers
3 views

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 ...
0
votes
0answers
12 views

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) ...
0
votes
0answers
6 views

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 ...
0
votes
1answer
15 views

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 ...
0
votes
0answers
8 views

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 ...
0
votes
0answers
11 views

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 ...
0
votes
0answers
17 views

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 ...
0
votes
0answers
6 views

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) ...
1
vote
0answers
9 views

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 ...
0
votes
0answers
11 views

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 ...
0
votes
0answers
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 ...
2
votes
0answers
11 views

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 ...
0
votes
0answers
6 views

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 ...
0
votes
1answer
25 views

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 ...
0
votes
0answers
9 views

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 ...
0
votes
0answers
10 views

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 ...
1
vote
0answers
13 views

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 ...
1
vote
0answers
9 views

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 ...
3
votes
0answers
15 views

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 ...
0
votes
0answers
8 views

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
0
votes
0answers
8 views

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 ...
-1
votes
0answers
8 views

log likelihood of density with a sum

I have the following density function, which is a marginal density of a compound Poisson distribution $f_{Y(w)}(y;\theta,\lambda,\alpha)=\sum\limits_{n=1}^\infty\frac{ \left\lbrace \lambda w)^{1- ...
-1
votes
0answers
8 views

How to explain the correlation between the mean of each element and it's corresponding PC1 coefficient in a data.frame?

I am doing some PCA analysis by R now,I have a data,which is a data.frame:a,ncol(a) =1000,nrow(a)=100,each row represent a sample,each col represent a feature,so when I use R do PCA analysis like ...
0
votes
0answers
5 views

How to Derive Score function and Information matrix for variance components in linear mixed effects model

Consider a linear mixed effects model, $Y_i = X_i \boldsymbol{\beta} + Z_i b_i$, where $b_i \sim N(0, D)$; $D$ is the variance covariance matrix $(2\times2)$ of the random effects terms. So the ...
1
vote
3answers
96 views

Small data set and linear regression

If I have a small data set (30 samples) am I more likely to obtain a statistically significant result? From my understanding if there are any relationships within the data set then they will be over ...
1
vote
1answer
44 views

Plot regression with interaction in R

I did a regression analysis with the following variables: Predictor = dummy variable, dependent Variable = metric, moderator variable = metric. I now want to show my results in a figure. The ...
1
vote
0answers
4 views

How to implement Gaussian process using GPML toolbox with known output noise?

I want to implement a simple regression model using Gaussian process. I chose GPML toolbox of Rasmussen for simplicity. My question is how we can let the toolbox know that we already have a different ...
4
votes
0answers
10 views

Robust option in Stata: why are the p values computed using a Student distribution?

The commonly used "robust" option in the regress command of Stata gives standard errors using the Huber-White sandwich estimators. The t statistic also uses these standard errors. However I have ...
0
votes
1answer
7 views

Intercept in random effects mixed model no longer significant

When I add a categorical fixed effect to my mixed model (with one random effect and three continuous fixed effects) the intercept is no longer statistically significant. Does this mean that the newly ...
0
votes
0answers
5 views

How to interpret change in intercept when a random effect is added to a mixed model

I have a fixed effect model, constructed in SAS using Proc Mixed as: proc mixed data= etc...; model ca = p t s /solution; run; which yields the following ...
0
votes
0answers
9 views

What algorithm can give me a probability-ranking on text-classifaction problems

I'm trying to classify e-mails using tokens in the text and headers. What I would like to know is which class a new e-mail most likely belongs to. The answer could be more than one class or could ...
0
votes
0answers
11 views

MLE for any distrubution using R [on hold]

I am constructing a joint density for Bayesian network ...
1
vote
2answers
31 views

Analyzing residuals in logistic regression

Greetings statistics experts, I am having a try with the kaggle titanic dataset and am wondering what to do with the residuals after fitting models. In the case of linear regression you can look at a ...
0
votes
0answers
5 views

Create scales from binary data

I am currently struggling with a statistics problem, I am in over my head, off the bus as one can say. As part of a research I am measuring incumbent response strategies to the perceived threat of ...
2
votes
2answers
622 views

Quarter is to quartile as half is to…?

Is there one word to describe the sections of data on either side of the median? I'd guess "half", but it seems like there ought be something better...
0
votes
0answers
6 views

Can a Naive Bayes Model predict using pattern alone?

Say I have a set of data abc-def-ghi jkl-mno-pqr stu-vwx-yza and lots of other training samples which are catagorized as **names*. The above dataset does not have ...
2
votes
1answer
9 views

Using variables that are only available for part of the data-set in a classification model

I have Data X1, X2, and y. X1 has the same variables as X2, + some extra variables that X2 does not have. I want to use the data X2 to predict binary variable y. I suspect the extra variables In ...
2
votes
2answers
31 views

Distribution of the exponential of a mixture?

Suppose that $X$ is distributed as a finite mixture of normals $$\sum_{j=1}^k w_j \phi(x;\mu_j,\sigma_j^2).$$ Is $\exp(X)$ distributed as a finite mixture of log-normal distributions?
4
votes
0answers
29 views

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 ...
0
votes
2answers
28 views

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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