# All Questions

9 views

### PhD in biostatistics

I have an interview with a graduate school that is a top university, but the graduate program from the biostatistics department is somewhat new, and thus is not top ranked. however, their medical ...
4 views

### Incremental Aggregation: need some clarification

I have started some self study on Data mining algorithm. Recently I came accross a problem. I need your hint: Given a Data Warehouse with e.g. 10 million entries, additional 1000 entries arrive each ...
7 views

### Statistical Significance of Turnaround Time

My laboratory recently implemented MALDI-TOF MS for identification of gram negative rods in blood cultures. I collected data retrospectively from laboratory reports comparing the time from isolation ...
7 views

### What is divergence in indicators/oscillators?

What is the direct cause of divergence in indicators/oscillators? Is it because of using the close price? How could I filter it out or isolate it? This would be useful to extract for a predictive ...
2 views

### Reporting sensitivity/specificity using a random process?

I'm using a method that involves cross-validation to make predictions on my dataset. As it splits the data randomly, I will end up with different results (I believe this is an example of a stochastic ...
11 views

### Distribution of a binary matrix times a Bernoulli vector

Suppose we have the vector $\mathbf{Y} = (Y_{1},\ldots,Y_{n})$ where $Y_{i} \sim \textrm{Bernoulli}(p_{i})$ independently. For the applications I have in mind, $n$ will typically be several thousand, ...
3 views

### Is there a SAS equivalent for JMP's life distribution?

I have a work flow where I use SAS to pull and prepare my data into censored data, and then open the SAS dataset in JMP and perform a life distribution analysis on the data. More often than not I use ...
35 views

### What statistical analysis did they do in this paper?

This is really a beginner question. I have to perform a statistical analysis which is exactly the same as the one conducted in the table shown in the picture. Specifically, how to calcolate the ...
3 views

### interpreting y axis of a partial dependence plots

I have read through other topics on partial dependence plots and most of them are on how you actually plot them with different packages, not how you can accurately interpret them, So: I have been ...
4 views

### Aggregating Results for pvclust

What is the best way to summarize the means or medians of the clusters identified by pvclust? I have done it before with hclust using the cutree command to identify clusters. I have then aggregated ...
5 views

### Price index - Bill method and Rate method

Can someone explaing the difference between these two methods for calculating price indices, i.e. how is index calculated? Or more precisely, what exactly is determined from the Bill method and the ...
5 views

### Standard errors of estimates in multi factorial LMEM

This question may already be well-answered as it seems relatively straight forward, but my search of existing posts has failed... apologies if it is redundant. I am building a linear mixed effects ...
10 views

### What is the Fourier Transform of a brownian motion?

I looked into this article http://en.wikipedia.org/wiki/Brownian_noise and it says that: If we have a brownian motion $W(t) = \int _{0}^{t} dW(s)$, then given that the spectral density of white noise ...
31 views

### How to prove that the Fourier Transform of white noise is flat?

If we take $X_n$ a series a random vector with its components each having a probability distribution with zero mean and finite variance, and are statistically independent. How do we prove that the ...
15 views

### Possible to code contrasts comparing each level to grand mean with no reference category?

I'm working on a health care outcome regression model using the deviation contrast scheme described on the UCLA SAS help page here for a collection of dichotomous predictor variables measuring medical ...
11 views

### Shortcomings of logistic regression [on hold]

I've recently started exploring logistic regression for modeling purposes and well... it's just performing pretty poorly. Apologies for a very broad question, but I just can't figure out why! Here's ...
7 views

### What is the distribution of the random variablle [on hold]

An aircraft passenger is tested to check if he is infected by H1N1 virus.
15 views

### (binary) Matrix completion with less known data

Recently, I meet such problems, I call it matrix completion problem. For example, the row denotes the users and the column denotes items. And If one user like the ...
4 views

### Simulation of CI of amount of values in different intervals by adding noise to original data

I am having a hard time trying to solve this problem, so maybe some of you guys can sort it out. I have a large data set containing a value describing the thermal comfort in buildings called PMV. The ...
8 views

### How do I report the data from a Cox proportional hazard regression model on SPSS

I was just wondering if there is a set way to write the results within a CPH model, I have obtained results from SPSS and I have values for Sig B and the 95% Confidence interval. What I am after is ...
7 views

### Variable selection that splits factor levels

This question is related to previous ones but I believe distinct. I am primarily interested in prediction and I have access to LASSO variable selection (but without factor level grouping) using the ...
6 views

### Ggplot gives “arguments imply differing number of rows” error in geom_point while it isn't true - how to debug? [migrated]

I have two objects of type Large SpatialPointsDataFrame named st2 and st10. They come from the same source. They both plot without problems with: plot(st2) or ...
11 views

### Question on SPSS Mantel_Haenzsel output

SPSS provides these three statistics as output for the crosstabs command STATISTICS=CMH(1): Tests of Homogeneity of the Odds Ratio Tests of Conditional Independence Mantel-Haenszel Common Odds Ratio ...
8 views

### How do I install and use Shogun toolbox in matlab? [on hold]

I want to use Shogun toolbox in matlab (windows) but their installation guide is not clear. Does anyone know simple steps to install shogun toolbox in matlab?
14 views

### Strange behaviour of list in R [migrated]

I ran on a very strange behaviour. I am trying to evaluate a rather long list (Generated code). ...
6 views

### Linear model for RCBD

Hi i am told to write a linear model for my stats assignment under an RCBD. ...
8 views

### The Shogun Machine Learning toolbox for SVM with precomputed kernel and zero bias

Can I use the Shogun Machine Learning toolbox for SVM with precomputed kernel and zero bias. I should be able to input pre-computed kernel and I also should be able to set bias zero.
4 views

### mean queue delay ( nonpreemtive priority)

I'm trying to solve a problem where all arriving items (arrival exponential $\lambda = 1/5$) are divided into into groups, those who are served within 5 units of time and those who have their service ...
16 views

### Discrete Choice Models

for mulitnomial (or mixed) logit models, when the choice set is too large, either strategic sampling or random sampling of the choice set can be used. My question would be: Is that also true in ...
18 views

### Distribution of random sample of confidence intervals containing the true mean

Given 50 random samples, each of size 25, from a normal distribution with mean 20 and standard deviation 5. From each of the 50 samples, you can find a 90% confidence interval for the mean. Let Y be a ...
20 views

### Can quadratic constraints be handled by Bayesian methods?

I want to solve a regression method whose parameters are under quadratic constraint a'*a=1. Is there any method in Bayesian statistics to handle this constraint? Thank you in advance.
20 views

### You will randomly select 10 balls from the box with replacement what is $E(\bar X)$

A box contains 100 numbered balls - 21 with the number 1, 36 with the number 2 and 43 with the number 3. You will randomly select 10 balls from the box with replacement and you take the mean of the ...
10 views

### How to adjust data to remove influence of one or more features

For my first real data science project I would like to develop a model which better reflects review quality than "useful" votes. I am working with Yelp's latest Academic data set but this thinking ...
4 views

### Method to estimate times of individual impulses from composite response

I have a detector that registers a sequence of "hits" over a period of time. Each hit produces a signal that has the approximate form ...
24 views

### Best way to determine normality of data

I believe there are many ways to determine if data is normal or not: histogram shape QQ plot skewness kurtosis shapiro test. Which of the above is the best way to determine if data is normal and ...
7 views

### Correspondence analysis reconstitution formula

I have a question about the reconstitution formula for the correspondence analysis. Let X be the observation matrix with variables by columns and observations by rows. I look for a decomposition  ...
10 views

### Sampling For Correlation

Suppose we have population P that is split into large number of close size sub-populations (e.g. country is split to zips). For each sub-population a small sample was drawn and average of a variable X ...
4 views

### Passing a function with parameters as an argument to another function in R [migrated]

Consider an example: I want to pass a function with or without parameters to another function and use it in the following way: ...
13 views

### Multicollinearity, feature selection for discriminant analysis and the error rate

I have a question regarding feature selection in LDA/QDA and deciding to eliminate variables to find an optimal model (lowest misclassification rate) I'm looking at how quadratic and linear ...
12 views

### The Binomial Distribution

I am trying to understand why when asked for the probability at least 1 success does it take the form 1-P(X=0) or 1-BINOM.DIST(0,1,.18,1). I am trying to understand this logic. Can you explain in such ...
17 views

### Why sandwich estimators aren't always used in OLS regression?

I asked before what is the intuition behind sandwich estimators. I must still missing something because I don't understand why sandwich estimators are not always applied to OLS residuals. Can you ...
6 views

### Is it possible to calculate the covariance btwn data and a subset of the data?

I have a regular and complete time-series vector and have created a subset of this vector based on a particular sampling algorithm (say every 10th value). To calculate the error variance of this ...
17 views

### Probability selection of elements from a set

If we have a set $S= \{s_1,s_2,..,s_n\}$ and each element in the set $S$ has an assigned probability $P_n$. Then a selection process is applied to the set $S$ such that, each element $S_n \in$ $S$ is ...
4 views

### error for xreg and newxreg matrix size in an arima model

I am using auto.arima to forecast a daily data and used holiday and weekday dummies as regressors. I am getting an error which does not make sense. When I want to predict a 7 step ahead forecast, it ...
7 views

### Team level analysis: how to aggregate control variables such as tenure, gender and working status?

I'm currently conducting research on a team level analysis (59 teams) in which i estimate the effect of voice climate -> team voice behavior, team voice behavior -> team learning behavior, and, team ...
28 views

### Did I meet my goal? [on hold]

Based on below did I meet the goal of < 10 minutes H0 = Median 15 Ha=Median less than 15 results Count (N) =207 Count for test= 188 Median= 10 Wilcoxon Statisic =2517.50 p value (1-sides)=0.000
19 views

### paired-sample t-test

I have taken weight measurements before and after a treatment. When I run a paired sample t-test and if there is a significant change, would it be possible to make the claim "95% of the time ...
22 views

### Can I say there would be only 2 groups with such features in this data and prove it using cluster analysis?

I assume that there would be two groups that will emerge within the data with my assumed features. I run cluster analysis and best number of cluster (elbow, dendrogram, etc.) shows it will be 2 and ...
15 views

### Do assumptions for estimators affect population parameters?

TL;DR: Specifying a model (a collection of restrictions over a sample space) specifies the model parameters. Specifying an estimation procedure adds additional number of restrictions (assumptions?). ...
25 views

### Why only full ARIMA models in auto.arima?

It seems that the auto.arima() function in the forecast package in R only considers full ...

15 30 50 per page