# All Questions

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### Is there any way to manipulate the titles of a ctree plot? [migrated]

Is there any way to change the title sizes of a ctree plot? Use the following variables to quickly set up a ctree plot ...
17 views

### Defining 'core' categories

Given a categorical variable, is there a way to define 'most common' categories? Consider, for example, a variable with 1000 categories. Obviously, these categories could be populated more or less ...
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### Infinite fourth moment and maximum entropy

Alright, I expect this is a silly question, but I don't actually know, so. Suppose there is some random variable that's distributed on the reals, and all I know about the distribution is its mean ...
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### Varying Non-Linear Parameters Based on Groups in R

I'm trying to develop a non-linear model, but I'd like to have the values for the parameters vary by group. To give you an example, a section of my data (just random numbers here) looks like: ...
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### Why do we prefer white noise and iid property?

EDIT When we add noise to system we say it is white noise. White noise will have a constant power spectral density, flat power spectrum. But what is the advantage of this? Why do we need iid ...
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### Sampling distribution of the mean of population that assume values only between 0 and 1

I'm trying to use central limit theorem to compute the mean of the sample, however the population where I'm sampling has value only between 0 and 1, can I use mean of the sample as mean of the ...
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### Designing bootstrap test for sparse data sets comparison

I have two categorical data sets which I would like to 'compare', that is, test whether they are drawn from the same population. Data sets are pretty large (up to 3 million entries), but appear to be ...
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### Universal, simple to use method of estimating 1 variable from 3 input variables

Im looking for a method that would allow me to estimate the value of 1 variable, described by 3 other variables. I have a set of measurement data collected with my camera. Each record consists of: ...
38 views

### Is this an example of Pooled OLS on Panel Data?

I am looking at a study that analyzes the effect of an infrastructure index on infant mortality and child mortality rates. The database has (asset) quintile level data for 47 different countries (from ...
26 views

### Is positive coefficient of price correct in a multiple regression model

I am currently undertaking forecasting of energy sales (kWh) for our industrial customers. From historical data gathered from 1993 to 2013, a graph of price per kwh against sales kwh shows a positive ...
19 views

### What is linear separability of classes and how to determine

This question may seem too trivial but my basics are not strong and I shall appreciate help in these concepts. For an n dimensional feature vector and 3 class problem does linear separability need to ...
7 views

### Regression with Census variables

I seek to model change in school performance over three years (2010 to 2012) using a number of socio-economic variables. The socio-economic data is available from two census periods: 2000 and 2010. I ...
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### Labels missing in R likert plot [migrated]

I am trying to plot a simple likert graph. Somehow I am not able to set the value of legends. Can anyone please tell me how can I do that? The following is the ...
18 views

### Clustering spherical-shaped data

I have a data set that consists of census data (5 attributes). Performing PCA, I found that the original data looks like a big chunk (please look at the first picture), and therefore, I decided to use ...
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### Compute confidence interval of Y/X, where Y and X are from different survey dataset?

Is it possible (and if so, how) to compute the confidence intervals of $\frac Y X$, where: $Y$ is the occurrence of events during a given period of time, and $X$ is the exposure of events during ...
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### R - Robust Ancova: Documentation/Examples for the ancmg function in the WRS package

Could anyone point me to a documentation or even better an example for the ancmg1 or ancmg functions of the WRS-package. There is a very short paragraph in the Wilcox' book about Robust Estimation, ...
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### Holtz-eakin, Whitney, Rosen Panel VAR

I'm trying to write a bit if R code to run the estimator in "Estimating Vector Autoregressions with Panel Data" Econometrica 56-6 (1988). I'm stuck on equation (3.12) I feel like $Z_{ir}$ and ...
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### counfounded batch effects in microarray dataset - can I do partial experiment redesign?

I'm working with a microarray data set where the batches are completely confounded treatment time, i.e. time t1 is all in batches b1 and b2, and time t2 is all in batches b3, b4, and b5. I know this ...
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### Bayes Interval Estimator using Neyman-Pearson

This problem is 9.56 from Casella-Berger. Let $X \sim f(x|\theta)$ and suppose that we want to estimate $\theta$ with an interval estimator $C$ using the loss L(\theta, A) = bLength(A(X)) - ...
28 views

### Finding optimal combination of parameters for clustering

I have a spreadsheet with one object per line. Each column contains values that are parameters of my objects (let's say length, width, height, weight, color). I can classify objects based on color and ...
6 views

### Using multinomial logit to rank observations

I'm trying to devise a model to rank a number of links according to their popularity. The links refer to upcoming events and job offers, and ideally I'd like to have a reasonably simple model that, ...
16 views

### Forecasting ar(p) for several counties

I have a data set of prices, these prices vary across time and across area. I have 18 areas with 32 time periods. What i want to do is forecast these prices, i have found that a AR(3) process fits ...
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### Missing values - for cases of “I do not know” or “Does not apply”

If I have a questionnaire with items on a Likert scale (1 to 5) and a sixth option "I do not know/Does not apply", is it okay to consider a "I do not know/Does not apply" response as a missing value ...
28 views

### Geodesic distance and mean

My data-set consists of points in globe. Suppose a User visits locations $l_1,l_2,\dots l_n$ (each location in $(lat, long)$ in the city with probability $p_1,p_2,\dots,p_n$ and I want to calculate ...
27 views

### Non normal residuals in multiple regression

I used height, weight, gender and age to regress on BMR (basal metabolic rate) and obtained the following qq plot of residuals I then regressed the above variables with log BMR and obtained the ...
23 views

### Model specification with Deflators: methodological question on forecast model

I am trying to build a model to predict one year ahead Earnings per share $(t+1)$ based on variables in year $t$. I’ve seen a lot of models in practice that use the following methodology: ...
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### Ordinal logistic regression with likert scales

I'm currently have a bit of difficulty determining how to analyze this data via logistic regression analysis. ...
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### Significance of variance components in Stata output

This might be trivial, but I'm used to HLM7 software output and now I'm switching to Stata (xtmixed). To give an example imagine I have students (level1) nested ...
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### Restoring original distribution from noisy observations

There is a known set of pairs $(y_i, \sigma_i)$ such that $y_i = x_i + \sigma_i N_i$ $N_i \sim \mathbf{N}(0,1)$ for all $i$ $x_i \sim \rho$ for all $i$ where $y$ is observed value, $x$ is true ...
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### Adding 2nd level variable into Multi-level Modelling in Stata

I'm used to HLM 7 software and now I'd like to switch to Stata, for multilevel modelling (xtmixed). To give an example imagine I have students(level1) nested within schools (level2). In HLM I can ...
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### Calculate confidence interval from point estimate and standard error

Im having a problem with calculating a confidence interval for an incidence rate ratio between two populations. Using PROC STDRATE from SAS, I've obtained the Incidence Rate Ratio (the difference in ...
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### Time in years(x axis) shows years in .5 interval - Time Series using R [migrated]

dsales1156ts<-ts(dsales1156,frequency=365,start=c(2011,6)) # This is my time series created with daily sales data when the first sale day is 6th January 2011. plot(dsales1156ts) The ...
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### Controlling overfitting with random forests for very high dimensional data

I'm using the randomForest package in R to analyse a genetic dataset of ca 100 samples with 10.000 genes. The samples are grouped into 5 classes, the smallest being only of 5 samples. I'm ultimately ...
322 views

### Why does bagging use bootstrap samples?

Bagging is the process of creating N learners on N different bootstrap samples, then taking the mean of their predictions. My question is: Why not use any other type of sampling? Why use bootstrap ...
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### Multigroup Longitudinal Item Response WinBUGS OpenBUGS

I was able to fit the Longitudinal IRT model in Winbugs for an ordinal response by extending the BUGS code I took from the paper by Curtis in JSS http://www.jstatsoft.org/v36/c01/paper/ However, I am ...
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### Using proper scoring rule to determine class membership from logistic regression

I am using logistic regression to predict likelihood of an event occurring. Ultimately, these probabilities are put into a production environment, where we focus as much as possible on hitting our ...
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### Are multi-class techniques for binary classifiers considered ensemble methods by definition?

I am studying ensemble methods which is loosely defined be: Combining models to a make a better model With multi-class techniques such as One-vs-one and ...
21 views

### Neural network and dynamical system

Dynamical systemsare those whose evolution can be described by a rule, evolves with time and is deterministic. In this context can I say that Neural networks have a rule of evolution which is the ...
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### Categorizing text into IPTC subjects

Does anyone know where I can find a corpus I can use to train a classifier into IPTC news categories (http://www.iptc.org/site/NewsCodes/) ? A google search was not very useful. Thank you