# Tagged Questions

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### Entropy as measure of order in data streams

Is it sound/allowed to use entropy as a measure of (non-) uniformity of a data stream? E.g. I calculate the Shannon entropy with the standard formula based on various measures in the data stream. ...
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### How to choose the right model among time series / survival analysis models?

I have a problem to model an interest decay to a product for marketing purposes. I simplify the problem. There is a new product for which the start day of sale is known (first day of purchase). We ...
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### How to quickly collect data (survey) from students in class?

What would be an easy and simple way to get online responses from students in class for use in class demonstrations. E.g. Height and Weight. A quick survey method in a computer class could make lab ...
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### Detecting a burst in real-time?

I'm tracking the value of a variable over time. I would like to detect if the value of the variable is bursting (having an unusual increase in it's value) in real-time. How can I do that?
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### Algorithm for real-time normalization of time-series data?

I'm working on an algorithm that takes in a vector of the most recent data point from a number of sensor streams and compares the euclidean distance to previous vectors. The problem is that the ...
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### Online Linear Regression with updates on past information

Suppose we have the following algorithm An online linear regression algorithm implemented using gradient descent. The step rate $\alpha$ is calculated using something that correlates to the squared ...
821 views

### Simple way to algorithmically identify a spike in recorded errors

We need an early warning system. I am dealing with a server that is known to have performance issues under load. Errors are recorded in a database along with a timestamp. There are some manual ...
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### Realtime data change detection

I have been asked to do some real time data analysis. The data values represent parameters of phone calls for a telco (like number of calls, call length, etc.) If the numbers suddenly drop or spike, ...
2k views

### Efficient online linear regression

I'm analysing some data where I would like to perform ordinary linear regression, however this is not possible as I am dealing with an on-line setting with a continuous stream of input data (which ...
407 views

### Graphing real-time data from a text file

I have a process which writes statistics from a server system to a file each second in this format: label1 label2 label3 344 666 787 344 849 344 939 994 344 ...
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### Period detection of a generic time series

This post is the continuation of another post related to a generic method for outlier detection in time series. Basically, at this point I'm interested in a robust way to discover the ...