All Questions

11 views

Relation of distributions

I want to predict a distribution using multiple related distributions. One method is to use multiple regression (the model specification is that the dependent variable, yi is a combination of the ...
11 views

Data At Varying Granularity

I'm sorry for asking such a simple question, but for some reason it is throwing me off. By "granularity" I mean level of the data. For example, say in the classic example of spam classification you ...
10 views

T-test to check a significance

Is it okay to perform independent sample T-test to test the effect of an health awareness intervention on male and female population registered at 300 polling booths in a town.
6 views

Binary Logiistc regression and covariates in SPSS

When running binary logistic regression, where there is an dependent variable, multiple independent variable and covariates, where do I put the covariates in SPSS? Would they go in the covariate box ...
21 views

Need direction in regards to probability based random value generation

I have a daily stream discharge data set spanning 10 years whose histogram looks like this: I would like to use it to set the distribution for a randomly chosen discharge for a given timestep. That ...
27 views

why do offline learning algorithms perform better than their online learning counterparts?

(I'm assuming infinite data, finite time for this comparison) I was wondering why it is exactly that online learning algorithms usually perform more poorly than their offline counter-parts.. Does ...
6 views

How do I calculate posterior probabilties from HMM?

The title may be misleading but I don't know if a better one exists. Consider the following figure: Basically, I want to replicate that. Its a bit easier for me because my HMM only has 12 states. ...
9 views

Role of Chi inverse distribution in the confidence interval of standard deviation

Suppose X = [11.17, 9.52, 10.69, 9.84, 10.84, 9.88, 10.28, 12.23, 18.4] is a random variable with mean and standard deviation as 11.48 and 2.77, respectively. If I calculate the lower and upper ...
12 views

Analysis of Feature Importances when features are dependent on one another

I can use random forests to determine which features are important when doing a prediction problem; for example. < height, weight, IQ measure> -> Is considered obese? Applying random forests ...
17 views

Which logistic model should I use in Stata when I have a mix of categorical and scalar variables?

I want to run a regression in Stata. The dependent variable is a scalar categorical variable indicating life satisfaction ls (1= satisfied, 2= intermediate, 3= ...
332 views

Does high number of values outside of 95% Confidence Interval imply non-normality?

I am looking at the errors of my model, i.e. difference between predicted outputs and actual values. Finding a mean and standard deviation, I found that many values (sometimes more than 50%) are ...
25 views

Do these random variables satisfy Lindeberg's condition?

I have the followig sequences: $Pr(X_n=n)=Pr(X_n=-n)=0.5$ $Pr(X_n=2^{n/2})=Pr(X_n=-2^{n/2})=0.5$ I have to show whether they satisfy Lindeberg's condition or not, but this condition is a bit ...
6 views

Binary Classification vs. Aggregating Multi-Class Predictions

Sorry for the convoluted question, I'm sure there is a better way to phrase this. Basically, say I have a 5-class target vector, but I'm only interested in membership in a subset of the classes. For ...
19 views

What is the confidence interval for model that is supposed to have mean of 'zero'?

I'm trying to analyze some dataset. I have a model. This model predicts some values. There are real values also known. I calculated the differences between the predicted and real outputs. Ideally, the ...
13 views

What does muhaz return?

A pretty basic question. I have read somewhere that the muhaz function in muhaz package will return the baseline hazard rate for COX model. The muhaz document states that it "Estimates the hazard ...
15 views

How to simulate a random variable from a matrix variate distribution?

I am trying to simulate a random variable from the matrix variate normal distribution but have not seen any literature on it. If somebody could point me in the right direction for that or if they ...
25 views

Optimization failure in HoltWinters [on hold]

I am using HoltWintersto fit the exponential model on the data. The data shows trend as well as seasonal pattern.Getting the following error message: ...
20 views

Multi-class Classification using SVM with PCA

I'm doing an image classification task and the number of features of each example image is pretty huge (3,072: # pixels in each image). I'm thinking of using PCA to reduce the # features of each image ...
22 views

How to determine the sample size, if standard deviation, population mean, sample mean and precision is given?

Determine the sample size if sample standard deviation is 6, population mean : 25, sample mean = 23 and the degree of precision is 99%
6 views

Wavelet transform of Gaussian function [on hold]

What is the wavelet transform of Gaussian function? Any continuous wavelet can be used.
8 views

R: Error with mlogit Conjoint modelling - system singularity

I am building choice models on a dates about coffee preferences. I have 5 alternatives: Brand, Cup, Price, Certification and Local Community Support. The data looks like this: ...
36 views

Using classical methods to explain bayesian approach to confidence interval estimation

I'm using bayesian techniques on R to calculate a 50% confidence interval for a parameter lambdastar which has a prior distribution gamma(alpha,alpha). I am simulating 10000 random samples of size 10 ...
18 views

Logistic regression model [duplicate]

Does one always have to standardize all coefficients in logistic regression models? Also does matlab automatically standardize coefficients or does this have to be done by the user? Thanks for any ...
13 views

How to plot a linegraph in SPSS with respect to the data? [migrated]

Hi all, Above you'll see a line-graph plotted with SPSS. I want to improve this line-graph according to its data. Meaning that some elements are not presented correctly: (1) I deliberately ...
10 views

EM algorithm - data imputation

Suppose we have iid sample of random vector $(X,Y,Z)$, where $x_i, y_i, z_i$ denotes corresponding realizations for the components. Assume also, that $(X,Y,Z)$ has a three-dimensional Gaussian ...
24 views

R - Number of days since last occurrence [migrated]

I have a data frame that looks like this: ...
180 views

Analyzing up/down patterns in short time-series data

I have not worked very frequently with time-series data, so am looking for some pointers as to how best proceed with this particular question. Let's say I have the following data - graphed below: ...
16 views

Adding number of observations in a histogram using gglpot [on hold]

My dataset looks as follows: ...
52 views

How to implement model in R?

i would like your help to implement this model in R or more explicity where yt = monthly mean values μi = mean value in month i, i = 1 . . . 12 . I1;t = Indicator series for month i of the ...
13 views

Why Would bagging perform better than boosting for the Naive Bayes Classification Model?

When I use SVD in Rapidminer, Boosting performs about 10% better with that model than with Bagging, but with Naive Bayes, the opposite is true. Why is this?
15 views

Calculating $\bar c$ in C chart

In studying C chart I came accross this problem in Statistical Process control by Douglas .C.Montgomary. In this exercise it says: A control chart is used to control the fraction of non ...
13 views

Example of multi-way clustering robust standard errors: puzzling results

I am trying to get a grasp on Cameron, Gelbach and Miller (2011) robust inference with multiway clustering. As I understand, bottom line is that ignoring clustering may result in standard errors ...
15 views

Statistics - (bivariate data) Planning an Inquiry

I have to conduct a statistical inquiry that is representative of a population. You have to choose from a list of situations, and my choice was to measure the weight and length of carrots. The ...
17 views

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Different results from quasipoisson models when using glm and winbugs

I used glm and winbugs to estimate quasipoisson models. I think the results should be very similar theoretically but they are not. Coefficients from winbugs are quite larger than those from glm. Does ...
153 views

Area within a given number of standard deviations from given mean

I have a variable with mean value of 18.85 and standard deviation of 1.45. I want to define the area that is covered by 1.45 standard deviations left and 1.45 standard deviations on the right side ...
20 views

Forecastability and Coefficient of Variation

I'm trying to get a sense check here. When determining "forecastability" for sales data, I tend to use the CV. However, this is highly susceptible to seasonality and outliers. As such, I was ...
21 views

Rearrange boxplot with ggplot [on hold]

My data looks as follows: X=cbind(var1=rbinom(100,1,0.26),var2=rbinom(100,1,0.01), var3=rbinom(100,1,0.07),var4=rbinom(100,1,0.09),var5=rbinom(100,1,0.004)) If ...
7 views

Data transformation using copulas

I've heard about the use of copulas to transform data. For instance, supposedly it's applied to data that is non-normal to make it look more normal. However, I don't quite understand how this is done. ...
23 views

Survival analysis for matched set cohort data - Methods for absolute and relative risks?

BACKGROUND I have a matched data set with 10,000 cases and 20,000 controls. Cases are defined as such due to a diagnosis of COPD (Chronic Obstructive Pulmonary Disease - a lung disease caused by ...
14 views

conjoint analysis_how to keep coefficients constant and make vary intercept

As a conclusion of a case, I have to derive a more accurate estimation of consumers’ part-worth for different levels of different attributes, and I need to find a way to make intercept vary across ...
4 views

finding critical categories within index

There exists network readiness index (NRI). 10 categories forms this index. Each category has subindicators. NRI index is measure four more than 100 countries. My goal is to identify critical ...
27 views

$\hat{\beta}^{(M)}_i\sim \hat{\beta}^{(N)}_i$ for linear regression?

Consider an i.i.d. sample $(X_1, Y_1), \dots, (X_N, Y_N)$, where each $X_i$ and $Y_i$ are $n$-dimensional column vectors, let $M \leq N$ and denote by $\hat{\beta}^{(M)}$ and $\hat{\beta}^{(N)}$ the ...
25 views

How to estimate the correlated individual components from a sum, for a random process?

Assume that there are $N$ realisations of five individual, random variables$X_1$, $X_2$, $X_3$, $X_4$ and $X_5$, which in general could be correlated. We define another random variable ...
33 views

Why do we estimate population parameters using statistic?

I had been studying statistics, I have a doubt that I couldn't find the answer of. Its related to estimating population parameters using statistic. Suppose we have a population size of 10000, we want ...
31 views

Understanding sample complexity in the context of uniform convergence

I was reading Andrew Ng's notes and on page 6 he mentions (uniform convergence): $$Pr[\forall h \in \mathcal{H}_{finite}|\epsilon(h_i)-\hat{\epsilon}(h_j)| \leq \gamma] \geq 1-2ke^{-2\gamma^2m}$$ ...
8 views

Permutation on multiple Pairwise Comparison with least square means in R 3.1.2

I'm working on a study where I employed an analysis of covariance (Ancova) with unbalanced factors. I used permutation tests to obtain p-values for my estimates since my observation does not come from ...