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7
votes
2answers
258 views

Compression theory, practice, for time series with values in a space of distributions (say of a real random variable)

Example of problem: Part of our research team is working on providing operationally wind power forecast. Usually, since there are different time scalse that interest forecast user, a forecast is ...
4
votes
1answer
2k views

Non-linear regression fails to converge, but fit appears good

I'm fitting a 4 parameter nonlinear regression model to multiple datasets, some of which fail to converge, however, the parameters output after a failure provide a fit that looks good, if not ...
7
votes
4answers
3k views

Validating an existing questionnaire into another language

I am doing research and trying to use a questionnaire that is available in English in another language. Is there a systematic approach for validating a questionnaire in another language? What ...
1
vote
1answer
463 views

Spline function with unknown knots

Does anybody know whether R has a package/routine for estimating spline function with unknown number of knots?
4
votes
1answer
321 views

Generating survival times in days or in years

When generating survival times to simulate Cox proportional hazards models, does it matter to generate them in days or in years? In theory, I guess it does not matter. But in practice? Is there a ...
15
votes
3answers
13k views

Probability formula for a multivariate-bernoulli distribution

I need a formula for the probability of an event in a n-variate Bernoulli distribution $X\in\{0,1\}^n$ with given $P(X_i=1)=p_i$ probabilities for a single element and for pairs of elements $P(X_i=1 \...
3
votes
2answers
1k views

Is there a standard format for presenting a data analysis report based on a questionnaire?

I am doing some class work and I was wondering if there is a universally accepted format for analyzing and presenting the data in a Word document for data gathered from questionnaires.
2
votes
4answers
3k views

Justifying normal approximation of experimental data

Background: In connection with the question here I came upon a more interesting question. I believe the question is large and distinct enough to have it's own thread. Of course I might be mistaken, ...
3
votes
1answer
3k views

Bayesian additive regression trees (BART) for classification analysis of gene expression data

I am interested in applying Bayesian additive regression trees (BART) for classification analysis of gene expression data. I am relatively new to R (and Bioconductor packages) and I am unable to find ...
7
votes
2answers
23k views

Analysis of covariance in R

How do you carry out analysis of covariance using R? How do you interpret the results? A practical example will be highly appreciated.
10
votes
2answers
14k views

Formal statistical test for whether a process is a white noise

Is there a formal statistical test to test if process is a white noise?
25
votes
3answers
102k views

What is a white noise process?

What is the best way of defining white noise process so it is intuitive and easy to understand?
3
votes
1answer
312 views

Is it possible to correct for violating the assumption of independence for nonparametric tests?

Is it possible to correct for violating the assumption of independence for nonparametric tests? I have a categorical independent variable and a categorical and binary dependent variable, and each ...
3
votes
3answers
433 views

Binomial Probability Question

Given two basketball players. John made 38/50 free throws. Mike made 80/100 free throws. What is probability that Mike is better at free throws than John?
5
votes
1answer
1k views

How can I effectively summarize and visualize time series of employee activities?

I am managing many people entering data into a database. I have a log of user, date, time, table, and action that each person makes: ...
10
votes
1answer
380 views

How to quantify redundancy of features?

I have three features that I use to solve a classification problem. Originally, these features produced boolean values, so I could evaluate their redundancy by looking at how much the sets of positive ...
14
votes
3answers
9k views

GLMNET or LARS for computing LASSO solutions?

I would like to get the coefficients for the LASSO problem $$||Y-X\beta||+\lambda ||\beta||_1.$$ The problem is that glmnet and lars functions give different answers. For the glmnet function I ask ...
3
votes
1answer
522 views

Error creating parser in readHTMLTable

readHTMLTable seems pretty robust, but when I try to use it on this page, I get an error. Any ideas what it means or how I could get around it? The page's biggest table is nested inside another ...
5
votes
1answer
143 views

Meta-analysis of 3 regions' data for 5 years

Can we do a meta-analysis of data of 3 regions. A particular disease was treated with the same treatment but implemented thoroughly in 2 regions and not so thoroughly in 1 region. How to proceed with ...
6
votes
2answers
486 views

Question about combining hazard ratios - Maybe Simpson's paradox?

I’m reviewing an article, and can’t give details but here is the situation, and it’s got me puzzled Patients were divided into 4 categories (call them A B C and D), which were exhaustive and ...
11
votes
2answers
13k views

Using poisson regression for continuous data?

Can the poisson distribution be used to analyze continuous data as well as discrete data? I have a few data sets where response variables are continuous, but resemble a poisson distribution rather ...
17
votes
3answers
1k views

When is interactive data visualization useful to use?

While preparing for a talk I will give soon, I recently started digging into two major (Free) tools for interactive data visualization: GGobi and mondrian - both offer a great range of capabilities (...
2
votes
1answer
1k views

Matlab image blending

Hey guys. I got two images from video frames. They have a certain portion of overlap. After warping one of them, I'm currently trying to blend them together. In other words, I would like to stitch ...
3
votes
2answers
4k views

How to obtain in R a good formula for glm (general linear models) to predict a binomial variable?

Is there a package or library that can help me suggest a formula given the independent variables which will work well in glm, for example this formula can be something like x^2+log(y)+Z, it does not ...
3
votes
2answers
14k views

Egger’s linear regression method intercept in meta analysis

In Meta analysis, how to interpret the Egger’s linear regression method intercept (B0) 10.34631, 95% confidence interval (1.05905, 19.63357), with t=3.54535, df=3. The 1-tailed p-value (recommended) ...
5
votes
2answers
4k views

Number of trials required from a binomial distribution to get the desired odds

This question may have been asked before, but I couldn't find it. So, here goes. From about 3000 data points that can be characterized as "wins" or "losses" (binomial), it turns out that there are ...
5
votes
3answers
2k views

Effect of missing data and outliers on least square estimation

Why is it that "missing data" and "outliers" can affect the performance of least square estimation?
26
votes
2answers
1k views

Does the distribution $\log(1 + x^{-2}) / 2\pi$ have a name?

I ran across this density the other day. Has someone given this a name? $f(x) = \log(1 + x^{-2}) / 2\pi$ The density is infinite at the origin and it also has fat tails. I saw it used as a prior ...
4
votes
2answers
3k views

Parameter estimation for normal distribution in Java

Given a set of data (~5000 values) I'd like to draw random samples from the same distribution as the original data. The problem is there is no way to know for sure what distribution the original data ...
9
votes
1answer
3k views

Bayesian inference for multinomial distribution with asymmetric prior knowledge?

Suppose I will be getting some samples from a binomial distribution. One way to model my prior knowledge is with a Beta distribution with parameters $\alpha$ and $\beta$. As I understand it, this is ...
1
vote
2answers
350 views

Log-scale with concentrated data using integers

I have a data set with a range of 0 to 65,000. The vast majority of data points (it is a huge sample) are concentrated between 0 and 1000. There is only one point that has 65,000. I want to plot ...
2
votes
2answers
5k views

Normal distribution necessary to assess moderating and mediating effects?

Is linear regression only suitable for variables with a normal distribution? If so, is there an alternative nonparametric test to test mediation or moderation?
2
votes
2answers
909 views

Seeing if estimators are unbiased

I have the pdf $$f(y ; \theta) = \frac{1}{\theta} \exp( \frac{-y}{\theta}), \ y > 0$$ and I'm supposed to determine if the following two estimators are unbiased or not: $ \hat \theta = nY_{min} $...
3
votes
1answer
4k views

Statistical Analysis for Perception Survey

Context: A sample of people were asked to provide ratings of their impression of jeepneys using a Likert Scale. Age, gender, household income, and so on was also obtained. Dangerous: strongly ...
21
votes
4answers
18k views

Calculating required sample size, precision of variance estimate?

Background I have a variable with an unknown distribution. I have 500 samples, but I would like demonstrate the precision with which I can calculate variance, e.g. to argue that a sample size of 500 ...
8
votes
1answer
6k views

What does “case-control” and “cross-sectional” mean in the context of logistic modeling?

While studying logistic modeling, I read the following statement The fact that only odds ratios, not individual risks, can be estimated from logistic modeling in case-control or cross-sectional ...
4
votes
1answer
479 views

Means and imputation of log-normal variables

The geometric mean is the appropriate measure of central tendency for log-normally distributed variables. However, the arithmetic mean still has some use in relation to log-normal variables - in ...
3
votes
2answers
657 views

Repeated measures using R [closed]

How do I carry out a repeated measures analysis using R?
33
votes
4answers
16k views

How do I fit a multilevel model for over-dispersed poisson outcomes?

I want to fit a multilevel GLMM with a Poisson distribution (with over-dispersion) using R. At the moment I am using lme4 but I noticed that recently the ...
4
votes
2answers
607 views

Logarithmic regression with individual errors

If I have a dataset of $N$ pairs ($x_i$,$y_i$) where each $y_i$ has an individual error $\sigma_{y_i}$, I can incorporate this into regression by using the inverse of this as weights. If I now do ...
12
votes
1answer
329 views

Online, scalable statistical methods

This was inspired by Efficient online linear regression, which I found very interesting. Are there any texts or resources devoted to large-scale statistical computing, by which computing with ...
11
votes
1answer
1k views

Documented/reproducible examples of successful real-world applications of econometric methods?

This question might sound very broad, but here is what I am looking for. I know there are many excellent books about econometric methods, and many excellent expository articles about econometric ...
3
votes
1answer
157 views

Creating groups with multi-dimensional data?

I'm trying to figure out the best way of creating groups in a dataset with many dimensions. I have 1000 measurements, and each measurement has 40 dimensions. The measurements are of neighborhoods with ...
5
votes
2answers
557 views

What is the right statistical test to use when attesting claims like “60% people switched over from group A to group B”?

My problem is this: There are 52 people divided into 5 groups: A, B, C, D, and E. From stage 1 to stage 2, they either stay in the same groups, or change groups. The following table shows how many ...
3
votes
1answer
1k views

Normal distribution and weight of babies problem

X is the weight of a baby when born (in gram). If the distribution of X is N(3315, 575) and Y is the number of babies with weight lower than 2719 in a random sample of 25, then P[Y≤4] is about...? I'...
3
votes
1answer
196 views

Function timings in the Matrix package

In order to test the Matrix package in R, I ran the following piece of code: ...
2
votes
1answer
774 views

Aggregating results from Arima runs R

/edit: To clarify: The mtable function from the memisc package does exactly what I need, but unfortunately does not work with arima models. Similar to this question: I have multiple Arima models, ...
57
votes
8answers
6k views

Why continue to teach and use hypothesis testing (when confidence intervals are available)?

Why continue to teach and use hypothesis testing (with all its difficult concepts and which are among the most statistical sins) for problems where there is an interval estimator (confidence, ...
1
vote
2answers
2k views

How to pull data formatted for Matlab into R?

I just ran a vendor-supplied program that converts data from their proprietary binary format to what they call a "Matlab format". There are two resulting files from the conversion, a "filename.dat" ...
15
votes
1answer
1k views

What is the expected value of modified Dirichlet distribution? (integration problem)

It is easy to produce a random variable with Dirichlet distribution using Gamma variables with the same scale parameter. If: $ X_i \sim \text{Gamma}(\alpha_i, \beta) $ Then: $ \left(\frac{X_1}{\...

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