# All Questions

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### how i apply singular value decomposition on PCA? [on hold]

i have the covariance matrix XX^T where c=1/n-1(XX^T) SVDX=U S^2 V^T how i compute left singular vector ,singular value segma and right vector V^T? my data is x=100 with 2D.
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### R + Model + web service [on hold]

I would like to interface R with some other language (C#/Python/anything easy to use) to provide it with a web service (or other technology) to an other application developed in C#. R => black box ...
2 views

### Summing mixed models regression coefficients

Let's say i have 3 variables. Food, toys and clothes, measuring my big family's expenses. I have tons of observations but my damn kids are horrible bureaucrats, hence i have a lot of missing data. ...
11 views

### Difference between non significant coefficient p-values and variable exclusion using AIC

I am trying to fit a linear regression model with two continuous explanatory variables and one factor with two levels. Rather than predictability, I am especially interested in the interpretability of ...
9 views

### Memory error with LSTM in Keras

CONTEXT Hi I am using udibr/headlines fantastic github project. The project goal is to "Automatically generate headlines to short articles" and i find it very interesting since it does abstractive ...
8 views

### Calculate probability of a measurement assuming a uniform distribution around a mean

Assuming a uniform distribution and given it's mean value, can I calculate the probability of a particular value occurring? This is a real world problem. The expected value is 3.35, so I guess that ...
5 views

### difference between saliency object detection and semantic segmentation?

Seems that saliency object detection is just foreground/background segmentation, which is a simple case of semantic segmentation
12 views

### Autoregressive and moving-average models [on hold]

I have been trying to fit AR and MA models separately using ACF and PACF but unable to progress using STATA. I have run the ACF and PACF plots at 95%. ACF is cutting off at lag 11 and PACF at lag 8. ...
9 views

### Modelling dependence between two groups but not within effects in ANOVA

I have two conditions and in each condition, the same participants took part. however, I am not interested in how the value of an observation changes between the two conditions for each participant (i....
10 views

### Time series cross-validation, calculate RMSE for different forecasting horizions

Following Rob J. Hyndman suggestions on how to do cross validation for time series ( http://robjhyndman.com/hyndsight/tscvexample/ ), I modified his original code to evaluate how RMSE (not MAE) ...
6 views

### how principal component analysis find independent class between the data?

i have x=100 with 2D I'ld like to reduce dimension using PCA . my question is how i use 2 class i mean 2 color in my data using matlap.i need full example for reduce dimension using PCA by matlap not ...
5 views

### Kendall W for continuous data

Simple question: can I use the Kendall W test for continuous data? Cuz I used it for a bunch of continuous variables and almost all coefficients are very close to 1, with p-values very very very small ...
11 views

### forecast using an ARIMA Model

I'm using the R function auto.arima to fit an arima model for a time series, the result is an ARIMA(2,1,1). After that I apply the ...
19 views

### Reduce feature levels

I would like to know if someone knows of a way to group the number of levels of a feature that has 100's (even 1000's) of levels to a smaller number of levels - also, what number levels it should ...
2 views

### what is the estimated variance of predictions from mixed model?

I have fitted the following lmer model (assume it is "correct") with lme4: Y ~ X1 + X2 + X3 + (1 | year) + (1 | site) + (1 | site:year) where X1-X3 are ...
18 views

### What statistical test I should apply for these type of data?

I am new to statistics. I have doubt on what statistical test I should apply for my data? There are two factors in my data: how stimuli are presented and what stimuli are presented. Stimuli are ...
28 views

### How to compute frequency distribution in R? [migrated]

Actually there are many functions which I don't know what to use to calculate it X = rnorm(100) Lets assume I have a normally distributed vector called X. I don'...
30 views

### Is the sample correlation coefficient an unbiased estimator of the population correlation coefficient?

Is it true that $R_{X,Y}$ is an unbiased estimator for $\rho_{X,Y}$? That is, $$\mathbf{E}\left[R_{X,Y}\right]=\rho_{X,Y}?$$ If not, what is the unbiased estimator for $\rho_{X,Y}$? (Is it analogous ...
11 views

### Statistics Question [on hold]

Researchers conducted a study in which they invited 85 nutrition experts to an ice cream social (Wansink et al., 2006). These experts were randomly given either a 17- or a 34-ounce bowl, and they were ...
8 views

### Which nonparametric test should I use

I am currently doing an experiment to test whether there is a significant difference between test results of a control group of steel bars of good shape and another group of corroded steel bars. I do ...
12 views

### How to convert SAS model to lme4 model?

I want to run a linear mixed model on a dependent variable DV that is collected under two different Condition at three different ...
11 views

### Uncertainty on the standard deviation of data set, when the data points are uncertain

I have a set of four data points (x,y), and I would like to describe the spread of the data about the mean in both the x-direction and in the y-direction. Each individual data point has an uncertainty ...
13 views

### 2d points distribution with shifted centroid

How can I have a distribution with centroid being away from center? i.e. points distribution starts out dense, and then goes on to become sparse, but with NO sudden transition? Pl find the image ...
10 views

### Can we set smoothing parameter to zero in mgcv package? [on hold]

Is there anyway to set mgcv package in R to apply no smoothing parameter in penalized regression, so that it turns to an ordinary spline regression?
7 views

### How can I do a CFA model of a questionnaire that has optional likert items?

I want to do a CFA model in which some of the items of one of the factors are optional. Said items are presented in a 5 point likert scale like the rest, but add a check mark to indicate that the item ...
19 views

### Problem involving P.D.F. containing an indicator variable

Let $X_1, X_2, \ldots$ be independently and identically distributed random variables with probability density functions: $$f(x) = \alpha \;x^{-(\alpha+1)} \; I_{(x>1)}, \; \; \alpha > 0.$$ For ...
19 views

### Attempting to create histograms in R [on hold]

I am trying to write a function in R that will generate a histogram for me. My current code is as follows. ...
8 views

### How do I correctly use Between-Subjects Factor(s) for exploratory variables on a 6-level Within-Subject repeated-measures ANOVA?

When analyzing data using a repeated measures ANOVA with multiple exploratory variables, there are four methods I could use, each of which produces different results. Which of these is the correct ...
8 views

### I want to perform a regression analysis on a Hospital Charge Data Analysis [on hold]

I have a dataset from the following website: https://www.data.gov/health/ which I am using in my final project. I want to perform a regression analysis. My attributes are DRG(diagnosis related drug), ...
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### Limit-bound continuous data, how to compare multiple distributions?

We are doing a simple experiment looking at the effect of smell on taste. 200 subjects are given a liquid to taste and asked to rate the favorability of the taste on a scale from 1 to 20. The subjects ...
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### Regression Analysis of Stratified Samples

What is happening in standard survey libraries in statistical software when "strata" are declared in e.g. regression analysis? Are strata typically treated as fixed effects? More broadly, how might ...