# All Questions

21 views

### Lasso as an optimization problem

Following my previous question in this topic, I have two questions First: why my R code does not produce similar results to lasso? In this case I use an already developed package and find the ...
4 views

### Shock event values in Linear Aggregate Definition of AutoRegressive Process

I am beginner in Time Series and studying (self study) at the derivation of the relation between AR process of Deviations and the Linear Filter process of actual values of Time Series. Have this ...
14 views

### Do I need data standardization before t-SNE?

In my knowledge, t-SNE use sphere or diagonal normal distribution to represent the distance between point. So I guess that the distance is biased by the scale of respective features. To my surprise, ...
8 views

### Concentration inequalities for product of gaussians

Are there any concentration inequalities (i.e. probability bounds on how a random variable deviates from its expectation) for the product of $n$ gaussian random variables with zero means and equal ...
11 views

### Are the data stationary or non-stationary and seasonality?

I want to use Arima model for forecasting wind speed.I plot my data. Then i plot ACF and PACF. I used ADF test and KPSS test and they said that data are stationary and doesnt need differencing but ...
16 views

### Structural Break - Stata

I have used Stata to run a time series multiple regression. I know that there is in fact a structural break in the data and the point at which it occurs; therefore, I have estimated the regression ...
41 views

### Central Limit Theorem Equation

I was wondering what the difference is between $Z_n=\frac{S_n-n\mu}{\sigma \sqrt{n}}=\frac{X_1+\ldots+X_n -n\mu}{\sigma \sqrt{n}}$ and $Z_n=\frac{X-n\mu}{\sigma/\sqrt{n}}$? What is the benefit of ...
18 views

### moving average: applied to time series equation

If I have an equation representing a time series, such as the following $$y(t) = y(t-1) + y(t-2)$$ But I am not given $y(t-1)$ or $y(t-2)$, so hence this recursive function is not given any initial ...
9 views

### Extensions of bsts and CausalImpact to non-Gaussian exponential family distributions

The bsts and CausalImpact packages implement a state space time series model with an optional regularized regression component. ...
13 views

I am trying to do seasonal ARIMA(0,1,1) model using matlab But I am a little confused about the results. The drawing of standard normal quantils and the standardized residuals are shown below: my ...
21 views

### Can I use a Bayes factor to compare cells in a contingency table?

I'm trying to compare which features of a website more active and less active users make use of. I've divided up the users into "active" and "inactive" and there are several page types they can visit. ...
24 views

### Could anyone help me check my gibbs sampling code? [on hold]

I am now trying to write a Gibbs Sampling code based on the posteriors from a paper "Bayesian Regularization via Graph Laplacian", writer: Fei Liu, et. When I run the code, it always show the error: ...
5 views

### Estimate of local slope (or tendency to “correction”) in time series

I have multiple time series of values aggregated at the weekly level. In short, I'm interested in finding local estimates of slopes for each week for each time series. An example of one of my time ...
15 views

### How do I calculate the probability level in which I can rule something out?

The question asks "At what probability level can you rule out a 10% larger slope", given the data, with a measured uncertainty of 0.13 in the y.  \begin{array}{cc} x & y \\ 1.0 & 1.1 \\ 2.0 ...
10 views

### What should be the covariance matrices and weights for initializing EM/GMM with kmeans?

It's typical to initialize EM for Gaussian Mixture Models using the result of kmeans clustering. However, kmeans only gives you the means (centers) of the starting GMM, but EM initialization often ...
34 views

### T-test with only certain values that form the mean and standard deviation

If I'm running a simple 1-sample t-test, and I have x-bar, s, n, and mu, where p-hat and s come from the following type of numbers: ...
12 views

### How do you combine data with multiple datasets? [migrated]

I'm having trouble combining a bunch of different data sets together. When I combine them, the variables v1, v2, and id combine into two separate columns where there's 3 different numbers per cell ...
30 views

### help me with this please [on hold]

Analyze the following statement: Michele watched videos of other soccer teams' plays, and she played better against those teams. Is the statement an example of correlation or causation? a:No ...
18 views

### Instrumental variable analysis after (propensity) matching

I am trying to replicate the methods used in this paper by Paul Rosenbaum and colleagues (Near-Far matching). I have been studying the methods in the referenced papers by Michael Baoicchi. My work ...
23 views

### How do you do a nonparametric quantile regression in SAS?

I want to do a nonparametric quantile regression in SAS and I can't, for the life of me, figure out how to do it. All the examples I see don't do a good job of explaining the code that is used and why ...
11 views

### Visualize Sensitivity Results Using Combinations of Means and Standard Deviations of Two Normally Distributed Variables

I ran a sensitivity of my model, sampling the response space using two normally distributed variables. I used four nested repetition loops to generate this data, recording the average output of the ...
71 views

### When to not use R squared [duplicate]

I recently graduated graduate school and am looking for a proof on R squared. Specifically when to not use it. I really remember a professor impressing upon me multiple times not to report R squared ...
13 views

### Where can I find good references regarding to noise filtering and prediction in time series?

I want to model the error structure of every certain time period obtained from the past errors produced by the predictions of nonlinear time series. I would like to know if someone knows specialized ...
7 views

### How can I obtain the Simulations in CausalImpact package? [on hold]

Currently we are using your package CausalImpact to evaluate the effect of different interventions over the accident occurrence in different firms. I address to you in order to ask you if there is any ...
69 views

### What to do if residuals are not normally distributed?

I was wondering what to do with the following non-normal distribution of residuals of my multiple regression. Normality test of standardized residual ...
37 views

### Can you perform an ANOVA on r-values (correlation values)?

I am doing neuroimaging research yielding what is essentially a correlational analysis wherein my output is a brain's-worth of r-values (so like 15000 voxels worth of r-values). In this particular ...
14 views

### ANCOVA without between subjects factor

this might seem like a stupid question but my knowledge of statistics has become fuzzy over the years. I would like to perform an ANCOVA without using a between subjects factor. Is that possible? I ...
8 views

### Comparing hurdle models to negative binomial models

I'm trying to compare the AIC or log-likelihood of a negative binomial GLM to a hurdle type approach, consisting of a binomial GLM for the presence/absence of a count and the counts modelled with a ...
5 views

### why are these uplift estimates different?

I recently stumbled upon an ODSC presentation: Machine Learning Based Personalization Using Uplift Analytics: Examples and Applications Uplift wherein two methods for "uplift" estimation are provided: ...
40 views

### What is the difference between a $\log_{10}$ and logit transformation?

What is the difference between a $\log_{10}$ and logit transformation? I have tried to find the answer elsewhere but cannot find a strict distinction.
6 views

### r ggplot 2 - set different fill colors for different facets [migrated]

Using ggplot2 in R, I want to set the fill parameter to be different for each facet. Here is some simplified code (Also ...
60 views

### PCA vs. Linear Regression

Am taking Ng's Machine Learning class on Coursera and in the below slide he distinguishes PCA from Linear Regression. He says that in Linear Regression, we draw vertical lines from the data points ...
13 views

### How to perform Sensitivity Analysis of Bayesian network using R?

I know there are similar techniques for Sensitivity Analysis for Random Forests. I am looking for something similar for Bayesian Networks. I have built the Bayesian Network using bnlearn package in R. ...
11 views

### Business statistics question [on hold]

You are to conduct a sample survey to determine the mean family income in a rural area. The question is how many families should be sampled? In a pilot sample of 10 families, the standard deviation of ...
9 views

### How to report statistics results [on hold]

Community Looking for some good references detailing (examples) the reporting of statistics in publications. Jeff
15 views

### Calculating a pooled estimate

I am writing a systematic review on certain imaging studies and I was hoping to add a meta-analysis of the sensitivities of the various modalities reported on. My goal was to put together a forest ...
15 views

### Advice on imputation of multiple time series

Background In the first year of the study 60 streams had temperature data loggers installed (temperature measured every 30 seconds). The second year only 30 of these same streams had data loggers. ...
7 views

### Moving sum window based on the time [on hold]

I have a data frame and there are two variables where one is a numeric(x) and the other is a date(t). I would like to create a new variable which will calculate the sum of X in the last time window. ...
23 views

### What Percent of Neural Network is used while processing a single image

What percent (on average) of entire Neural network (say, AlexNet) is actually used while processing a single image. There should only a very small amount of network that should actually be utilized ...
14 views

### RandomForest MeanDecreaseAccuracy interpretation

I know there are already some questions regarding the interpretation of the MeanDecreaseAccuracy metric of the randomForest-package, but it's still unclear to me. My assumption was that each variable ...
10 views

### What distribution is appropriate for length of a signal (in days)?

I have a vector of "signal lengths", which is the amount of days a signal lasts once initially activated. For the purpose of confidence intervals and hypothesis testing, do I want to use a Poisson ...
39 views

### Why does Stouffer's method work?

It seems like a fairly straightforward question, but when I really think about it, Stouffer's method doesn't make sense to me. This is why: Assume a two-tailed hypothesis. You first calculate $z_i$ ...
8 views

### How can I ENTER a 4-way interaction in a hierarchical regression blocks in SPSS? [on hold]

I have 4 variables, and I want to compute their interaction in a hierarchical multiple regression. But I do not know how I put main and interaction of variables in blocks of hierarchical multiple ...
14 views

### How to draw a efficient sample variogram using gstat package in R?

I have a csv file named seoul3112, contains PM10 concentrations. please, download..I have tried to plot sample variogram and fit a model on it. ...
20 views

### Appropriate Sample Size Formula

I have a uniform distribution set which contains different similarity scores. This similarity scores is linked with documents in which I am planning to examine. However, this set is big, and it is ...
13 views

### The probability that several normally distributed random variables have a particular order

Let's say we have n random, independent variables $X_1,\ldots,X_n$ with normal distributions. Is there a reasonable way how to compute the probability that they have a particular order, for example ...
20 views

### How to calculate uncertainty in bacterial growth rates (or in the slope of any local regression)?

I'm using a plate reader to measure optical density of different bacterial strains so I can compare their responses (growth rates and changes in them over time) to stress conditions. The growth curves ...
16 views

### How to generate random numbers correlated to a given dataset in matlab [on hold]

I have a matrix x with 10,000 rows and 20 columns. I want to generate another new matrix of random numbers , y, where y is correlated to x with correlation coefficient q. Note that the matrix x is ...