# All Questions

111 views

### Anomaly Detection - a novice question

As I understood from my experimentation on some multivariate data-sets, anomaly detection (AD) heavily depends on the underlying distribution of data. Like, for ex., you can devise a method to detect ...
25 views

### Non-informative prior for regression model

I'm looking at p. 355 of Gelman's Bayesian Data Analysis (3rd ed.), for which there is no errata, and I see this: In the normal regression model, a convenient non-informative prior distribution ...
28 views

### Transforming time series of different time horizon to stationary

I have a list of monthly time series data with different time periods and different order of integration. I want to transform them all to stationary and a same time period. I noticed that the order ...
3 views

### Latent semantic indexing: how to get the low-rank document vectors?

I'm reading the book "Introduction to Information Retrieval" from p.414 to p.416 and I can't understand how the authors computed $C_2$ on p. 415 : http://nlp.stanford.edu/IR-book/pdf/18lsi.pdf They ...
4 views

### Understanding Differential Expression Analysis in Microarray Experiments

Can someone please provide me a simple explanation of how differential gene expression analysis works? I know that this method is described in [1] and used in the R package limma. [1] Smyth, Gordon ...
24 views

### Training and test data for Holt Winters Method

I am new to forecasting. I have weekly data. I want to forecast using the Holt-Winters method. Should I make training and test subsets of the data? How important are the training and test data?
39 views

### Forecasting: Different Model for 1 month, 2 month, 6 month forecasts?

I'm still trying to expand my statistics and forecasting technique knowledge. Right now I'm forecasting seasonal contact patterns, so the simplest model I can understand with seasonality is a ...
32 views

18 views

### Correlation vs Partial Correlation to explore relationship in data

I have a cognitive architecture solving a set of tasks. Also I have data of human subjects solving the same set of tasks. Now I want to see whether I can find a relationship between the performance ...
198 views

### how does Cox proportional hazards model deal with time-dependent variables

When considering time dependent data in survival analysis, you have multiple start-stop times for an individual subject with measurements for the covariates. If each season has a different size (for ...
9 views

### Down-sampling with building models (specifically random forests)

I was wondering if anyone had ever used down-sampling to build random forests with data that has unbalanced classes. Basically down-sampling samples (with replacement) x*min from the population where ...
21 views

### Multivariate Time Series

I am trying to learn multivariate time series using R. I have two time series and I want to see if I could use one of those to predict the other one, and after that check if the model holds or there ...
9 views

### Select range of dates above and below another date [migrated]

Consider these small dataframes a and b: ...
23 views

### T-Statistics - What is it actually infering? [on hold]

Hoping you can help me here. Could you explain the T-Statistics a little more to me? So far I understand how to compute it and why you compute it however I don't understand why it is considered of ...
150 views

### How to compare the effect of age on brain volume across different brain regions when the regions are of different sizes?

I am working on analyzing volumetric information extracted from the brain. In particular we would like to compare the strength of effects across three different regions (say x, y, and z). However, the ...