-1
votes
0answers
12 views

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.
0
votes
0answers
12 views

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 ...
0
votes
0answers
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. ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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
0
votes
0answers
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. ...
0
votes
0answers
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....
1
vote
0answers
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) ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
1
vote
1answer
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 ...
1
vote
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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'...
2
votes
1answer
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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 ...
0
votes
0answers
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?
0
votes
0answers
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 ...
-1
votes
0answers
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 ...
-1
votes
0answers
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. ...
0
votes
0answers
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 ...
0
votes
0answers
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), ...
0
votes
0answers
8 views

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 ...
0
votes
0answers
9 views

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 ...
0
votes
0answers
17 views

Generating smooth time series

I want to create a smooth time series that follows a non-linear simple model, for example something like this: $Y_{t} = 0.5(Y_{t-1})^{3/2} + \epsilon_{t}$. The important part to me is to have $Y_{t-...
0
votes
0answers
5 views

How to extract fixed coefficients from output of coxme in R? [on hold]

I tried using 'names' and 'str' function but they do not help me find the right label to use in order to extract the fixed coefficients from the output of coxme I would like to see the entire output ...
3
votes
0answers
12 views

Martingale process

Let $\zeta(t)$ be a process with independent increments and $M(t)=E(\exp(\zeta(t))) < \infty $, show that $M(t)^{-1}\exp(\zeta(t))$ is a martingale. So what I need to show is $$E(M(t)^{-1}\exp(\...
0
votes
0answers
6 views

Minimum sample size for non-stationary time series predictions

I'm not an expert about this topic. I'm trying to make a model to predict cpu usage. Imagine that I want to predict 5 months, What is the minimum sample size to perform the regression?. I've read a ...
3
votes
0answers
23 views

Restricted Boltzmann Machine : how is it used in machine learning?

Background: Yes, Restricted Boltzmann Machine (RBM) CAN be used to initiate the weights of a neural network. Also it CAN be used in a "layer-by-layer" way to build a deep belief network (that is, to ...
1
vote
0answers
23 views

Finding moments of the untruncated distribution from the moments of the truncated one

I would like to get the moments of a normal distribution from the moments of a two-sided truncated normal distribution in R. Their formulas are available on the truncated normal distribution ...
1
vote
0answers
9 views

Can I try several CFAs on the same data before choosing one for generating factor scores?

I'm interested in matching on latent constructs (see Raykov, 2012), and one way to do so is to match on factor scores generated by CFAs of the items (One could also match on the items themselves, but ...
2
votes
1answer
28 views

Logistic regression - correcting for differing quality of observations

I'm stuck with the following problem. I want to run a predictive logistic regression. My dependent variable is binary (0,1). My predictor is a continuous variable. However, the quality of ...
0
votes
0answers
8 views

Is using pairwise comparison instead of single label value a valid way to augment training data

There are many papers using siamese architecture to do pairwise ranking. For example: suppose my training set is $\{X,Y\}$, where $Y$ is the continuous value. I can find a regressor to minimize $\|h(X)...
0
votes
0answers
9 views

Similarity measure between groups of monetary values

Suppose I have 2 groups, with monetary values, like this: How could I get a measurement of similarity between these 2 groups? It could be just a hint for me to get started with, like a name of the ...
0
votes
0answers
12 views

Principal Component Analysis and generalized variance

I'm trying to prove that the first $k$ directions found by PCA maximize the generalized variance, i.e. the determinant of the covariance matrix. Basically, I'm trying to prove that $$ \...
0
votes
1answer
10 views

What is chance performance cut-off for a 2-part dichotomous response?

If subjects had to give 2-alternative forced choice responses for a task (Y/N) and then rate the certainty of their response (also 2-alternative forced choice: High/Low), and we analyzed their ...
1
vote
1answer
15 views

Should the underlying logic of the model evaluation criterion match with the estimation procedure?

Assume we have a parametric model with parameter $\beta$. We want to use this model to make predictions, e.g., credit card firm using some attributes $X$ of the customer to predict the default rate $Y$...
0
votes
0answers
12 views

Lee (1983) sample selection correction with accelerated failure time model (in Stata)

I am trying to replicate the selection control used by Henderson et al. (2006), which is derived from Lee (1983). Henderson et al study CEOs over time and try to control for the likelihood that a CEO ...
0
votes
0answers
12 views

How to normalised log likelihood, Pitt and Shephard (1999)?

I have a serious problem to understand this paper! Particularly page 13 (or 559)! I have a stocastic volatility model (without factors), namely $$ y_t = \epsilon_t \sigma \exp{\alpha_t/2},\ a_{t+1}=\...
0
votes
0answers
20 views

p-value for the McNemar's test

There's a question I wanted to ask with regards to the McNemar's test applied for case-control study. Suppose I have 2 models, I've fixed specificity and now I could construct the contingency table....
0
votes
0answers
11 views

Sample size determination for estimating a count

I want to estimate a simple variable: "**how many times my website is visited in 2015?". Suppose that I cannot count all visits to my website (it is expensive!), but I can count the connections on ...
3
votes
1answer
28 views

How to sample a truncated multinomial distribution?

I need an algorithm to sample a truncated multinomial distribution. That is, $$\vec x \sim \frac{1}{Z} \frac{p_1^{x_1} \dots p_k^{x_k}}{x_1!\dots x_k!}$$ where $Z$ is a normalization constant, $\vec ...
0
votes
0answers
16 views

In R, why is the survdiff function returning the p value = 0?

I want to obtain the pvalue of the three curves that are plotted. Here is the code that does a survdiff: ...

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