All Questions

2 views

Correlation or clustering of continuous score and discrete variable states

I have an experiment that produces a decimal score representing quality, and a bunch (5-30) of variables that each take on one of a set of discrete states. - The states are not meaningfully ...
4 views

Design of matrix of contrasts in R

I am doing some post-hoc comparisons (in lme4, but here I'll just present a simple linear model), and I am having a hard time making sure that I am building the right matrix of contrasts to test ...
8 views

statistical analysis with interval data

I have been assigned the task of helping someone who has collected some survey associated data related to some kind of government facilities provided to people. The data corresponding to small scale ...
4 views

How can I determine local minima from a Kernel Density Estimation?

I have a fairly large 1-dimensional array that I am trying to cluster. I came across several other questions on this site where the top answer is to use a Kernel Density Estimation and then locate ...
3 views

How do you test for trend in a generalized linear model, particularly for odd numbers of levels of a variable?

I'm trying to test for a trend across levels of a categorical variable using a contrast statement in a model and can not figure out how to do it when there are odd numbers of levels. Looking at SAS's ...
5 views

ANOVA and Count/Percent Data

I'm just starting to work with some count data and I'm still trying to understand some of the complexities of it, so any help would be greatly appreciated. First the simple version, and then the ...
5 views

Multiple comparisons when investigating consistency of a device

I am trying to compare the performance of two devices designed to cool anaesthetised patients. This is a substudy analysis and the patient allocation between the groups is not even. Once cooling was ...
6 views

Interpretation of the partial autocorrelation function for a pure MA process

I have been working with some time-series theory and I noticed something that I can understand "mathematically", but not based on the intuitive explanations of what the partial auto-correlation ...
7 views

In practice, how is the penalisation matrix for splines, created by smoothCon (package mgcv), specified?

Evaluating a smooth object with smoothCon provides, besides several other things, the ordinary "untouched" spline bases ...
7 views

Seasonal vs non-seasonal coefficients in R ARIMA

Let's say I have the two following ARIMA models: ARIMA(7,1,1) (no seasonality) ARIMA(6,1,1)(1,0,0)7 (seasonality of period 7). Are they conceptually the same? If so, why is that when I model ...
8 views

Problems running lmer after upgrading to R 3.1.1 [migrated]

I'm running Windows XP, and I recently upgraded to R 3.1.1 and updated all the packages. Oddly, I can't run a lmer on my own data any more. My code worked when I was using R 2.15. I also tried using ...
11 views

Average Growth Rate for Year 1 across 5 groups

I have a question that pertains to time series or more likely pertains just to simple math. Lets suppose that I am measuring the number of online visitors to 5 websites on a monthly basis, so I have ...
12 views

How to understand this “normalized product-moment correlation” description

I've recently come across this formula from an ITU-T standard in a project that I'm working on. The application of the formula is to compare two vectors containing some per frame statistics from two ...
11 views

Independence of effects in meta-analysis and meta-regression

In meta-analysis, I know that an important assumption is independence. Clearly, if we want to estimate a pooled effect size, its best if each effect comes from an independent sample of observers. ...
15 views

Categorical Variable with more than 50 levels

I am new to analysis. I would like to know relation between my 2 sets of categorical variables , Both my variables has more than 50 levels. Is it a good approach to create dummy variable and do the ...
12 views

Bayesian fitting - multiplying two probabilities with differing orders of magnitude

I am fitting a model to data using Bayesian inference. This is my first time of using this method. My posterior is P = p_prior * p_photometric * p_spectroscopic. ...
13 views

How to deal with categorical features.

Recently I am playing in the famous Big-Data website Kaggle. There is a Display Advertising Challenge. In this competition, you are giving a training file which include huge records. the records is ...
5 views

Epoch vs Incremental Update over Entire Dataset

In the context of neural networks, what is the difference between training like this: ...
30 views

Can I use Kolmogorov–Smirnov test on my Data?

I am not good in statistics so I desperately need your help. So I have this dataset of distributions, and I want to know if I can use the KS-test on it. the Idea is saying that the feature's ...
4 views

ggplot2: geom_polygon with no fill [migrated]

i hope, you dont need data for this problem, because i believe i am just making a stupid syntax error. The following code: ...
4 views

multivariate analyses for incomplete factorial design

We have conducted a survey experiment with varying amounts of incentive (factor 1 = I1, I2, I3, I4, I5). The experiment was conducted stepwise in three subsequent studies (factor 2 = S1, S2, S3). ...
3 views

permutation test with a distribution of correct values

I want to test my classifier performance using a permutation test. I know how to test one actual value against a null distribution of values generated by randomly reassigning labels to my two classes. ...
15 views

Is there a test for comparing principal components decompositions between samples?

Is there any test for comparing the directions, magnitudes, etc of PCA results for different samples? I'm leaving the nature of the test deliberately vague because I'd like to hear all the various ...
17 views

Is it possible to measure the independent variable with part of the dependent variable

I have Beta as my independent variable and Economic value added (EVA) as my dependent variable. To calculate EVA I need to use Cost of capital and to calculate that I have to use Beta, so is it ...
14 views

Curve-fitting and variance-stabilizing transforms

I'm working with data corrupted by a mixed Poisson-Gaussian noise model (for example with images gathered in astronomy or electron microscopy), and have been using the generalized Anscombe ...
20 views

Probability of picking numbers

I am doing an introductory course in statistics and I'm struggling with one question in particular. The question is: Suppose two people each have to select a number from 00 to 99 (therefore 100 ...
13 views

propensity score with SPSS and R plug-in

I have recently installed R-essential and the "psmatching" program. All went well, until I performed (actually tried to perform) the analysis. Basically, I have a cohort of patients, divided into two ...
13 views

is there a difference between semipartial correlation and regression coefficient in multiple regression?

I am preparing a presentation about multiple regression. Most of my sources seem to equal unstandardized coefficients in multiple regression with the semipartial correlation of that IV with the DV. ...
5 views

Likelihood Ratio as statistical test for Transfer Entropy with MatLab

I estimated a Transfer Entropy value TE(XY). Now I want to establish the statistical significance of the estimated value. Therefore I used the method of shuffled surrogates to estimate a shuffled ...
10 views

JAGS prior-based prediction

I'm trying to use rjags to predict what the curve-maximums will be for different groups of incomplete data (one metric x and one metric y). Here is an example of the indata: ...
8 views

Time Series Cross Sectional Analysis and Forecasting With R

cty time tl Argentina 2009_Q4 3 Argentina 2010_Q1 2 Argentina 2010_Q2 7 Argentina 2010_Q3 7 Argentina 2010_Q4 10 Argentina 2011_Q1 7 Argentina 2011_Q2 7 Argentina ...
14 views

Flexmix to test bimodality [on hold]

How to use flexmix in r to check the modality of dataset, for example I have a vector of some 100 numbers how should I apply flexmix to test whether this data has bimodality or trimodality? Thanks.
11 views

In the survival analysis package of R, survival, where do we specify the hazard functional form?

I am trying to fit either the coxph or survreg function with the Survival package. I would ...
8 views

Finding comparison metric/methods

I want to compare the performance of two algorithms. Please suggest me some metrics/methods to compare between the algorithms. Below is given a short description of the output of the algorithms. ...
21 views

Which Analysis to use? Likert Scale

I have 3 independent variables (1-5 Likert Scale) questions and I want to check how well these three can predict/explain my DV (1-5 Likert scale) The three independent variables are: 1. Quality of ...
25 views

Sales Forecasting using Support Vector Machine

I have sales data for last three years 2011-2013. I want to use Support Vector Machine technique in R to do the predictions. I just wanted to know that the approach that I am using is correct or not? ...
29 views

ratio of explanatory variables in linear regression

I wonder if anyone has any links or advice on specifying a ratio of two explanatory variables in a linear regression ie specifying the two independent variables plus their ratio. We have data where ...
8 views

Multilayer perceptron 3 classes

I need to create a MLP for 3 classes. I don't know to to do the structure. I thought that having one hidden layer (don't know how many nodes) and and output layer with 2 nodes would be enough, like ...
35 views

Surprisingly similar hypothesis tests

I would like to ask you for pairs or even triples of statistical tests which are, surprisingly, similar. By "similar" I mean they test essentially the same hypotheses and lead to approximately the ...
32 views

What measures would best describe average salary? [on hold]

Given are the monthly salaries of the Math Professors of a certain university. What measures would best describe average salary?
15 views

A data set with many variables having NA Values , Some NA Values is to be removed and in some variables mode value is to be imposed HOW [on hold]

I have a dataset with 25 variables.few variables carry Missing Value. AS R reads missing value as NA value, If not mistaken. I have to remove the missing value from one variable and in another ...
6 views

libsvm with diffrent count of Keypoints [migrated]

I would like to use libsvm for a keypoint detection algorithm. Each keypoint has 36 features, but each sample of an Object has a diffrent count of keypoints... Is it even possible to train with ...
13 views

Limitations of Genetic Programming?

From the implementation and tests I performed I start to wonder if GP (or LGP) can be used for anything else than symbolic regressions and ant move problems (which is not really programming). Did GP ...
13 views

Is there deep learning,especially RBM, code that is really good to do classification [on hold]

For example, I found some code , but they didn't do wake-sleep algorithms to adjust the weights. I am especially interested in the one that google brain used for recognizing "cat" from youtube, no ...
13 views

Estimation of TRANS_GUESS and EMIS_GUESS matrices in Baum-Welch algorithm

I would like to ask how do we estimate the probabilities in TRANS_GUESS and EMIS_GUESS matrices (see here http://www.mathworks.com/help/stats/hidden-markov-models-hmm.html#f8288 ) as an input for the ...
8 views

Polynomial Data Fitting for Two Unknown Equation

I have a kind of data and want to find the equation(poly coeff) of given data. For example equation for given sample data is simple a^2*b+10 ...
19 views

How to interpret residual plots from time series regression

I am doing a time series regression between 2 variables. I used the dynlm library in R. I'm trying to understand how to interpret the results. Could you please point out where I am getting it wrong: ...
17 views

Hidden Markov Models relationship

I have a question regarding a small investigation that I have been conducting into the relationship between the length of observation sequence, T, on which two decoders (BCJR and classic Viterbi) ...
I am currently trying to fit a survival analysis model which has the following survival function: $S(t) = \lambda_i e^{-\lambda_i t}$ but with $\lambda_i = e^{\beta_0 +\beta_1 log(1+X_i)}$ where ...