# All Questions

9 views

### Geocoded node map visualizers?

I'm looking to create a map like the one below for shipment volume between cities (which I have geocoded). I found the image below, however I'm wondering what other tools exist that can do similar ...
8 views

### Important Variable Direction in Random Forests

In a logistic regression a positive/negative beta tells you that the direction that variable works. Is there anything in the Random Forest variable importance measures that indicates the direction of ...
5 views

### Chi-squared Vs Mutual information

Is chi-squared feature selection better than Mutual information based feature selection mechanism?
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### Data set with negative silhouette

I want to construct data set 𝐷 in 2 dimension, with a clustering {𝐶1, 𝐶2} computed by k-means with the property: which full fills the condition: There exists a point $𝑜∈𝐷$ with a negative ...
4 views

### Interpreting a logarithmic difference as an error

This is a fairly simple question but I can't figure out which one is the correct approach. In astronomy it is usual to report age values via their base 10 logarithms instead of the actual value. So a ...
7 views

### find posterior distribution parameters by simulation

I've calculated the posterior distribution parameters of a variable X analytically and by simulation. But doesn't mach. X ~ Normal(mu,s=6).And the prior distribution of X is a Normal(mu=100,s=20). As ...
13 views

### Simple Linear Regression - Prediction Interval and Non-constant variance

I have two questions about a simple linear regression model. I want to use test1 scores to predict test2 scores. I am using R software. x=test1, y=test2, Let's say that both tests are scored from 1 ...
15 views

### Result of K-Means Algorithm Not Desired

I am learning about K-means algorithm, and I have generated a dataset with 150000 data points, with 10000 points per cluster. (Scatter plot at the bottom) When I run K-means on the dataset, I first ...
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### Choice of grouping in Chi-Squared test

Let's say I have a categorical variable. I try to test the null hypothesis that each category has the same count (of something) using a Pearson's Chi-Squared test. I may not be able to reject null ...
11 views

### Using Naive Bayes as vectorizer and SVM for classification in Java

0 down vote favorite I am trying to classify legal case documents which are in text format, in different folders like Civil, Land, Criminal, e.t.c, I intended using Naive Bayes as Vectoriser to get ...
23 views

### Transformation Chi-squared to Normal distribution

The relationship between the standard normal and the chi-squared distributions is well known. I was wondering though, is there a transformation that can lead from a $\chi^2 (1)$ back to a standard ...
11 views

### Setting up data sheet for ANOVA

I am trying to set up a data sheet for my project, which is on the number of men and women on each floor in a dorm. My hypothesis is that each floor (and therefor the dorm as well) will have more ...
14 views

### How to implement reduced-rank regression in R?

How can I fit reduced-rank regression with continuous response in R? I found the package VGAM but it only fits for discrete distributions...
14 views

### Matlab: Time lagged time series and its correlation

Let, $x_t = [y_t,y_{t-1},...,y_{t-p}]'$ where $y_t$ is the output of an autoregressive process of order p=2 excited by Gaussian white noise of zero mean. $y_t$ is a vector output of the AR process: ...
15 views

### 'Punishment Function' in Number of Knots in Splines?

I was considering using natural cubic splines for my prediction problem when I had a thought: In Ridge Regression, you set out to minimize the equation; F(X)=\lambda\sum_i ( b^2)+ ...
10 views

### Conceptual question on correlation matlab and implication [on hold]

Let, x = [1 0.9 0.1 -0.3]'. The formula for creating correlation matrix is E[x*x']. I have confusion related to implementation ...
12 views

### Regression - Censored Data

I am trying to create a linear regression model which will predict test scores of students based on previous test scores. x=test1, scores range from 1:100 y=test2, scores range from 2:50 I have ...
8 views

### AR(n) model with exponents

When we discuss a (time-series) model $AR(n) = \Sigma_{i=0}^n Y_{t-i} + \cdots + \epsilon_t$, we use $n$ to refer to the number of time steps back the autoregression includes. In other such models, we ...
8 views

### Kolmogorov-Smirnov and Hellinger distances

I am comparing two distributions with these two methods and sometimes I find no correlation between them! How is it possible? Which one is more believable? I use the D statistic from the KS test and ...
6 views

### A question about Dickey-Fuller Unit-Root Test

I am reading Dickey-Fuller Unit-Root Test in Time Series Analysis with Applications in R by Cryer and Chan and have trouble understanding some discussion on equation (6.4.1). So they took this ...
3 views

### What is the difference between Harris Corner Detection and SUSAN Corner Detection? [on hold]

What is the difference between Harris Corner Detection and SUSAN Corner Detection
3 views

### Conditionally remove rows that match in column A, based on column B in R using data.table [migrated]

Trying to fix a de-duplication problem using data.table in R. Column A is a list of names, some of which appear multiple times. Column B is a list of dates. There are a bunch of other columns that I ...
12 views

### Is a normal process mean reverting

A normal process has a lot of outcomes around the mean and then fewer and fewer outcomes away from the mean. From this, can we conclude that a normal process reverts to the mean whenever it gets a ...
4 views

### EM convergence when using em.hmm from PLIS

I use em.hmm function from PLIS package. I tried it on dimensions in range from 2 to 6. In every case of provided data (z-values) EM algorithm does not converge for dimensions 2, 5, 6. So, I wonder ...
15 views

### difference between confidence interval and prediction interval in the context of regression analysis and predictive modeling

When building prediction models, I always see the following concept 1) Confidence interval for regression model 2) Prediction interval 3) Confidence interval for predicted value I can understand ...
25 views

### Post-hoc after GLM: What does it exactly say?

Background: I have been asked to model the change of weight of a few animals undergoing experimentation via a simple GLM (General Linear Model). The data looks something like this. Note that all data ...
12 views

### balls-and-urns in PyMC

In trying to wrap my head around Bayesian statistics and PyMC I've been trying to program up a balls-and-urns example. Sadly, I'm failing miserably. Assume that I'm drawing balls from an urn and know ...
19 views

### Need clarification on a passage. (Autism Prevalence)

Passage verbatim: According to a review by Silverman et al. (2010), the incidence of autistic disorder is 0.6–1.0 percent in the population. The disorder is four times more common in males ...
5 views

### find optimal parameters for SVM from tune() in R= [migrated]

I am optimizing the gamma and cost variable using the tune function ...
13 views

### Square root of number of counts, or standard deviation of the mean?

I'm doing an experiment in radioactivity, where I measure the number of counts in a given time interval when a radioactive source is placed in front of a detector at a fixed distance. I repeat 3 times ...
10 views

### Perhaps easy about SPSS Chi Square and Bonferroni

Oh hello. I just have entered here. Best place for my question. Sorry for that question in other site's part. :) So perhaps it's easy question, but I encounter this problem first time. I go ...
4 views

### GLM - X.intercept equal to NA [duplicate]

What does it mean X.Intercept equal to NA as a result of glm summary ? Thanks. Coefficients: (1 not defined because of singularities) ...
8 views

### Kernel matrix is a covariance function

How to prove that the kernel matrix is actually a covariance matrix?
29 views

### Best linear unbiased estimator

I have a sample of N stocks. I have the following information: For each stock i, I have an estimate of variance (of returns) $\hat{\sigma}^2_{i}$. I also have a fitted variance, denoted by ...
23 views

### How to bootstrap panel data?

I'm fitting some machine learning algorithms (e.g. SVM) on my panel data. It's taking too long for my entire dataset, so I'm considering generating smaller samples from bootstrapping then fit the SVM ...
5 views

### assign asymmetric cost in SVM classification in R?

I know that we can set a symmetric cost in R for svm,how do we set an asymmetric cost? I want to do a grid optimization like the following: ...
43 views

### Quick Exploratory Analysis of Categorical Data

Does anyone know of a tool (preferably free) that does quick analysis of exploratory data mainly categorical with date. Using R and Python I can create time series and histograms, perform tests such ...
12 views

### In soft-margin SVM, is it guaranteed that some points will lie on the margin?

In soft-margin SVM, once we solve the dual-form optimization problem (using quadratic programming, which is guaranteed to converge on a global optimum because the problem is convex), we get a vector ...
5 views

### Question on Stationary & Cointegration Test (Augmented Dickey Fuller & Engle Granger test)

I'm performing the stationary and cointegration test on stock prices. What I'm confused is 1) the difference between ADF stationary test and ADF cointegration test. 2) Also, in ADF stationary test, ...
69 views

### “Dummy variable” versus “indicator variable” for nominal/categorical data

"Dummy variable" and "indicator variable" are labels frequently used terms to describe membership in a category with 0/1 coding; usually 0: Not a member of category, 1: Member of category. On ...
33 views

### Is there any other measure of the performance of a classifier than the area under the ROC curve?

I am trying to draw an ROC curve for a classifier and wondered to know if there is any other measure for the performance of the classifier than the AUC. And is there any free software that I can use ...
10 views

### DNA sequence classification

I have a database of 3190 instances of DNA consisting of 60 sequential DNA nucleotide positions classified according to 3 types: EI, IE, Other. I want to formulate a supervised classifier. At the ...
19 views

### What is the “pdm” stat in the “rms” R package?

I am new to the world of Regression in statistics and I have been doing a research in which I am building an ordinal logistic regression model (ORM). In order to fit my ORM model, I am using the 'orm' ...
12 views

### Neural Network Predicting Live Market Data (fun project for BTC prediction)

Made it just for fun - not for profit, wrote a neural network application that is predicting output from live data from exchange markets dealing with Bitcoin. Now just to clarify, i am not asking if ...
31 views

### Acceptable values for the intraclass correlation coefficient (empty model)

I'm using xtmixed in Stata to test a Hierarchical Linear Model. My problem is that variance at level 2 is about 4% of the total variance. So most of the variance is ...
32 views

### Probability of event happening after the last event

My question seems to be very trivial, but I'm still stuck with it. It's about probability calculations. Suppose you have a number of people that take a glass of water (event), time between 2 events is ...
11 views

### How to reconstruct the data? [duplicate]

I have compressed the data( seven sensors are measuring 125 days temperature) using Principal Component Analysis . Then How to reconstruct the data ? What formula should i use?
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### Model Selection with Competing risks in Cox regression

When doing cox proportional hazards regression one often has competing risks. The typical approach for this is to fit separate cox proportional hazards models for each risk, censoring the competing ...