All Questions

0
votes
0answers
2 views

McNemar or chi-square - test for group differences paired and unpaired data

I understand that the difference between a chi-square test of homogeneity and the McNemar test is that the chi square is used for unpaired data and the McNemar is used for paire data. Here's my ...
3
votes
2answers
351 views

How to analyse these data?

I am conducting an experiment investigating lineup accuracy and witness confidence. A long story short: we want to know what the pattern of false positives, hits and misses on a lineup task are ...
0
votes
0answers
5 views

Marginalizing product of multivariate normal distributions

How should I marginalize $F_{i}$ from the following probability distribution $$p(y_{i}|F_{i},\alpha, \Lambda, \Phi, \Sigma) = N(\alpha + \Lambda F_{i}, \Sigma)$$ in order to obtain ...
0
votes
0answers
4 views

Sampling related - Rejection sampling

I am new to Bayesian methods. I was going through a chapter on sampling. I have a few questions related to it. Please help me get these clarified. As far as I understand, rejection sampling will not ...
1
vote
0answers
10 views

Need direction in regards to probability based random value generation

I have a daily stream discharge data set spanning 10 years whose histogram looks like this: I would like to use it to set the distribution for a randomly chosen discharge for a given timestep. That ...
0
votes
0answers
4 views

Handling Sparse Data Frames - algorithm selection

I am new to machine learning/statistical modelling. I am trying to run a classification on a highly sparse dataset with 100 features, most of which are categorical (TRUE/FALSE) with the remaining ...
0
votes
0answers
2 views

k-mean clustering of week-times

I have data of meeting times. The data has weekday and hour of the day. I want to cluster the meeting times (I have reason to believe there are two different kinds of meetings that tend to occur at ...
0
votes
0answers
2 views

Sampling related - MCMC

This is a continuation of the following question. The previous link was related to rejection sampling. This is related to MCMC. Sampling related - Rejection sampling 1a. As far as I understand, the ...
0
votes
0answers
3 views

Choosing between two parameters based on the mean and the standard deviation of the error

I am trying to interpolate data under the assumption that I have the true data. The interpolated data is dependent on a parameter which I am trying to estimate. For each possible value of this ...
0
votes
0answers
3 views

How to determine if a U chart or a C chart to be used

This is regarding theory of attribute type control charts.In a question it is given data for the number of non confirmities per 1000 meters of wire. I have to calculate control limits for a ...
0
votes
0answers
4 views

Relation of distributions

I want to predict a distribution using multiple related distributions. One method is to use multiple regression (the model specification is that the dependent variable, yi is a combination of the ...
1
vote
0answers
6 views

Data At Varying Granularity

I'm sorry for asking such a simple question, but for some reason it is throwing me off. By "granularity" I mean level of the data. For example, say in the classic example of spam classification you ...
0
votes
0answers
7 views

T-test to check a significance

Is it okay to perform independent sample T-test to test the effect of an health awareness intervention on male and female population registered at 300 polling booths in a town.
1
vote
1answer
513 views

Comparing the result of a study which has unequal group sizes

I have conducted two user studies and in my studies I didn't have control over the group sizes. In each study users were put in groups and they were asked to perform some group activities. Here is the ...
1
vote
1answer
52 views

Area within a given number of standard deviations from given mean

I have a variable with mean value of 18.85 and standard deviation of 1.45. I want to define the area that is covered by 1.45 standard deviations left and 1.45 standard deviations on the right side ...
6
votes
4answers
140 views

Analyzing up/down patterns in short time-series data

I have not worked very frequently with time-series data, so am looking for some pointers as to how best proceed with this particular question. Let's say I have the following data - graphed below: ...
0
votes
0answers
3 views

Binary Logiistc regression and covariates in SPSS

When running binary logistic regression, where there is an dependent variable, multiple independent variable and covariates, where do I put the covariates in SPSS? Would they go in the covariate box ...
1
vote
0answers
21 views

why do offline learning algorithms perform better than their online learning counterparts?

(I'm assuming infinite data, finite time for this comparison) I was wondering why it is exactly that online learning algorithms usually perform more poorly than their offline counter-parts.. Does ...
0
votes
1answer
278 views

Topic models evaluation in Gensim

I've been experimenting with LDA topic modelling using Gensim. I couldn't seem to find any topic model evaluation facility in Gensim, which could report on the perplexity of a topic model on held-out ...
1
vote
2answers
551 views

Image Clustering with K-means - Postprocessing

I did some clustering on an image (each pixel is an observation that has 5 variables associated with it), I get pretty detailed results but they are a little bit noisey... I think. I used K-means. ...
0
votes
0answers
9 views

Role of Chi inverse distribution in the confidence interval of standard deviation

Suppose X = [11.17, 9.52, 10.69, 9.84, 10.84, 9.88, 10.28, 12.23, 18.4] is a random variable with mean and standard deviation as 11.48 and 2.77, respectively. If I calculate the lower and upper ...
-1
votes
1answer
10 views

Which logistic model should I use in Stata when I have a mix of categorical and scalar variables?

I want to run a regression in Stata. The dependent variable is a scalar categorical variable indicating life satisfaction ls (1= satisfied, 2= intermediate, 3= ...
1
vote
1answer
56 views

Mixed ANOVA post hoc analysis (and multiple comparisons)

I have a set of 12 subjects: 6 administred with drug A and 6 with drug B. For each subject two time-points have been collected (before and after drug treatment) for each analyte (over 6000). I had a ...
0
votes
1answer
16 views

Issues plotting a fitted SVM model's decision boundary using ggplot2's stat_contour()

I'm trying to figure out how to plot a decision boundary for a fitted svm model in ggplot2. Right now, I'm attempting to do so by using stat_contour. Here is my code with an example call to my ...
2
votes
2answers
63 views

Does high number of values outside of 95% Confidence Interval imply non-normality?

I am looking at the errors of my model, i.e. difference between predicted outputs and actual values. Finding a mean and standard deviation, I found that many values (sometimes more than 50%) are ...
0
votes
0answers
6 views

How do I calculate posterior probabilties from HMM?

The title may be misleading but I don't know if a better one exists. Consider the following figure: Basically, I want to replicate that. Its a bit easier for me because my HMM only has 12 states. ...
0
votes
0answers
11 views

Analysis of Feature Importances when features are dependent on one another

I can use random forests to determine which features are important when doing a prediction problem; for example. < height, weight, IQ measure> -> Is considered obese? Applying random forests ...
0
votes
1answer
71 views

Post-hoc test for slopes - phia package for R

I am trying to do a post-hoc test to make pairwise comparisons between slopes. I found a package called phia but is not available for the R version 2.13.2. Does ...
9
votes
4answers
173 views

How to generate a large full-rank random correlation matrix with some strong correlations present?

I would like to generate a random correlation matrix $\mathbf C$ of $n \times n$ size such that there are some moderately strong correlations present: square real symmetric matrix of $n \times n$ ...
0
votes
0answers
22 views

How to formulate the pdf and likelihood function in delay embedded space

PROBLEM STATEMENT: Let $Z$ be random variable in $d$ dimensional space expressed as $\{u_t = (u_t,u_{t+1},...,u_{t+d-1}| t=1,2,..,100\}$; $d=2$. So, $Z$ is obtained from $u$ after Takens Delay ...
2
votes
1answer
44 views

How to implement model in R?

i would like your help to implement this model in R or more explicity where yt = monthly mean values μi = mean value in month i, i = 1 . . . 12 . I1;t = Indicator series for month i of the ...
1
vote
1answer
235 views

Unit root test specifications?

I am puzzled as to what specification I should include in my unit root tests of the following data: . I will use ADF, KPSS and ZA tests. I can see there is a break in trend at observation 9. However, ...
2
votes
1answer
19 views

Do these random variables satisfy Lindeberg's condition?

I have the followig sequences: $Pr(X_n=n)=Pr(X_n=-n)=0.5$ $Pr(X_n=2^{n/2})=Pr(X_n=-2^{n/2})=0.5$ I have to show whether they satisfy Lindeberg's condition or not, but this condition is a bit ...
0
votes
2answers
251 views

Maximizing: likelihood vs likelihood ratio

Say I have an observed data set ($n_i$) and I want to obtain the best fit out of 10 data sets produced by a model dependent on a single parameter $a$ ($m_i(a)\;a=1..10$). Suppose I use a Poisson ...
0
votes
1answer
265 views

How get pvalue with a glmer model (lme4)

I am desperately looking a way to obtain the p-values for the fixed effects on my glmer model. Any idea ?? I found a lot of things for lmer model but nothing worked with the glmer ... thank all !
0
votes
1answer
6 views

Binary Classification vs. Aggregating Multi-Class Predictions

Sorry for the convoluted question, I'm sure there is a better way to phrase this. Basically, say I have a 5-class target vector, but I'm only interested in membership in a subset of the classes. For ...
1
vote
1answer
7 views

Sample modification or weighting for partially paired data?

I want to analzye age and gender related differences of serum levels of an antibiotic agent, which was administered to 1200 patients during 1700 infectious episodes (1-12 infectious episodes and thus ...
7
votes
2answers
219 views

Test to distinguish periodic from almost periodic data

Suppose I have some unknown function $f$ with domain $ℝ$, which I know to fulfill some reasonable conditions like continuity. I know the exact values of $f$ (because the data comes from a simulation) ...
0
votes
1answer
15 views

Statistics - (bivariate data) Planning an Inquiry

I have to conduct a statistical inquiry that is representative of a population. You have to choose from a list of situations, and my choice was to measure the weight and length of carrots. The ...
1
vote
0answers
18 views

What is the confidence interval for model that is supposed to have mean of 'zero'?

I'm trying to analyze some dataset. I have a model. This model predicts some values. There are real values also known. I calculated the differences between the predicted and real outputs. Ideally, the ...
0
votes
1answer
17 views

Multi-class Classification using SVM with PCA

I'm doing an image classification task and the number of features of each example image is pretty huge (3,072: # pixels in each image). I'm thinking of using PCA to reduce the # features of each image ...
0
votes
1answer
19 views

Optimization failure in HoltWinters [on hold]

I am using HoltWintersto fit the exponential model on the data. The data shows trend as well as seasonal pattern.Getting the following error message: ...
-1
votes
0answers
14 views
9
votes
1answer
1k views
+50

R and EViews differences in AR(1) estimates

The main problem is: I cannot obtain similar parameter estimates with EViews and R. For reasons I do not know myself, I need to estimate parameters for certain data using EViews. This is done by ...
0
votes
1answer
98 views

what statistical test should i use for three groups with different sample sizes?

What statistical test should I use if I have three independent groups of interval data and would want to check whether their means are significantly different? I'd also note that the samples sizes of ...
0
votes
0answers
16 views

How to determine the sample size, if standard deviation, population mean, sample mean and precision is given?

Determine the sample size if sample standard deviation is 6, population mean : 25, sample mean = 23 and the degree of precision is 99%
1
vote
0answers
15 views

How to simulate a random variable from a matrix variate distribution?

I am trying to simulate a random variable from the matrix variate normal distribution but have not seen any literature on it. If somebody could point me in the right direction for that or if they ...
0
votes
1answer
21 views

Linear regression with redundant features (perfect multicolinearity)

Suppose $X \sim N(0,1)$, $Z=X$, and $Y=X$. An ordinary least squares regression problem is solved: $min_{(b1,b2)} \|Y-(b1*X+b_2*Z)\|_{2}^2$ This is a strictly convex function which must have a ...
0
votes
1answer
8 views

Permutation on multiple Pairwise Comparison with least square means in R 3.1.2

I'm working on a study where I employed an analysis of covariance (Ancova) with unbalanced factors. I used permutation tests to obtain p-values for my estimates since my observation does not come from ...
4
votes
3answers
885 views

How to estimate vector autoregression & impulse response function with panel data

I am working on vector auto-regression (VARs) and impulse response function (IRFs) estimation based on panel data with 33 individuals over 77 quarters. How should this type of situation be analyzed? ...

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