Questions on the use of mathematical techniques to extract properties from given data. Consider if your question might be more suited for Cross Validated (stats.SE) instead.

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1answer
220 views

Html Tag counting - Rate of Change formula

I've been trying to a find a statistics-esque formula for calculating the rate of change for html tags which are either added or removed from various websites. So, for example, with the scraper I'm ...
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1answer
4k views

How to perform simple linear interpolation on a data set

With the following data set, what is the best way to interpolate the data for each time. ...
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0answers
52 views

How to quantify the volitility of a time series data?

I am currently working on a time series data and I would like to quantify how volatile it is. Here volatile I mean how "shaky" the series is. If the series is smooth than it is not volatile. I have ...
2
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1answer
75 views

How to transform data distributed around zero to make it closer to normal?

I have data that ranges continuously from $-1$ to $+1$, with lots of zeros in the middle. I want to transform the data to a normal distribution. How would I do this? My normal approach with data ...
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0answers
321 views

How should I calculate “fill rate”? People inquire about an item and then buy it days/months later?

So I have posts(people posting a want for an item) and then I have fills(the person actually getting the item) There are hundreds of posts per day but the fill for that item can be days or weeks away ...
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1answer
313 views

Equal interval data classification technique formula confusion

The formula for breaking a sequence of values into groups of equal ranges is: max - min / number of categories I would like to know why is it necessary to subtract the maximum value from the minimum ...
1
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1answer
180 views

How to create function that is a power law

If I have a starting and ending y value and know the range along the x-axis, how can I create a function that adheres to a power-law? Ex: I want the function to start at (1, 10), end at (1000,0). ...
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0answers
101 views

Jacobian approximation at given point without explicit derivatives expression

after solving a NLproblem with optimization method, I would like to compute confidence intervals, prediction bounds and standard deviation for these optimal parameters. Explicit formulas I have read ...
0
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2answers
72 views

Normalize $X$ to $0$ to $10$ scale with asymptotes at either end

I am trying to find a scaling function that mimics the gas gauge in a car. I would like to map a value to a $0$ to $10$ scale, on which I have two known points. For example: $X_1 = 2$, $Y_1 = 2.5$, ...
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1answer
2k views

time derivative of discrete data in simulink

I'm implementing a program in Java that was delivered in Simulink. My expertise is limited, and I'm stuck on converting a derivative block. The simulink code applies a du/dt block to the input data. ...
0
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1answer
349 views

Calculating number of draws in a series of team matches

May be this could be an easy problem but somehow cannot arrive to any conclusive result to this indecisiveness problem For a certain number of teams ($n$) playing a series of matches ($m$), and given ...
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2answers
158 views

Working out the “best” score based on quantity and ratio

I'm not an expert with mathematics so I hope I'm posting in the right place! I've got a lot of products which can be rated good, bad and OK by a user. What I'm having trouble with is finding which is ...
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3answers
175 views

'Squashing' a graph of data?

I have a vector of sample data that describes a divergent oscillation like in this image. I want to transform this data (just the data, not the system or anything), so that the data does converge ...
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1answer
225 views

How do i estimate an equation of best fit of a sort-of exponential equation given it's points?

There is an unnessarly long table of values of an item in a game that grants experience to a player based on one's level in the chosen skill. I think it would be much more appropriate to cite the ...
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3answers
663 views

Find parameters for exponential function fitting to datapoints

I have a set of datapoints, in this case the temperature of an object adjusting to the environment temperature over time. Because I know these kind of processes take the form of $$f(x)=Ae^{x/B}+C$$ I ...
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2answers
89 views

preliminary evaluation for forecasting models

Suppose I would like to use a method for data prediction, and that I have some empirical data (i.e., sequence of samples of the form [time, value]). Would it be possible to know in advance, based on ...
1
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1answer
84 views

Waveform filter - what's in the black box?

I'm trying to come up with an algorithm or filter that has the i/o characteristics in the image below (waveform plotted from audio data) .. I input a sine wave or saw and the resulting graphic is an ...
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0answers
33 views

How to symmetrically adjust data by removing certain value

Say I have a data set in the following format: {a:200, b: 100; c:400} The sum of a, b and c equals 700. Now, I have another value which is supposed to be the actual total say 500. How do I adjust ...
0
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1answer
51 views

Graphically representing low number of infractions against high activity volume

I have been presented with a dataset that looks at work volume and safety infractions. A sample table: A sample chart: The issue we are having is trying to graphically represent it so that ...
2
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1answer
1k views

Understanding a Density Plot

I am currently plotting density plots in R to view the distribution of my data. An example density plot is here I understand N is the number of values in the data set and bandwidth is the the ...
3
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3answers
324 views

What would this curve be called?

In an resistor-capacitor circuit, the voltage stored is measured by taking the two values in Farads and Ohms - and the curve looks like this: What would this curve be called, logarithmic? ...
0
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1answer
126 views

Fitting two separate curves to a graph consistently?

I have a set of graphs with a large primary peak and a secondary peak that intersects the first and I want to fit two curves (one per peak) and find the point at which the two curves intersect for ...
1
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1answer
381 views

Curve fitting with upper and lower bounds for derivatives

I compute (at a great cost) upper and lower bounds $f_u(x)$ and $f_l(x)$ of an unknown function $f(x)$ at points $x$ in $[0,1]$. Now I am interested in an estimation of the derivative $f'(x)$. I ...
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2answers
159 views

weighted ratings

I have a form where users can rate presentations and they can say how knowledgeable they are on the subject. The range for both sets is 1-5. (1 being lousy and 5 being great) So for example, a user ...
1
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1answer
374 views

Given sample data with three data points, how do I predict or guess the 3rd data point when only given two data points?

I'm tracking data on a backup job that runs nightly on our server and using the historical data to predict data and job time growth. I have the following three data points for most of the records: ...
9
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4answers
2k views

Polynomial fitting where polynomial must be monotonically increasing

Given a set of monotonically increasing data points (in 2D), I want to fit a polynomial to the data which is monotonically increasing over the domain of the data. If the highest x value is 100, I ...
2
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1answer
7k views

Boxplots and bar graphs

I'm studying for the GRE and came across several questions that I was unable to answer in a practice booklet, even after looking at the answer and trying to work backwards, and searching google and ...
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2answers
137 views

Trying to find a meaningful statistical indicator to reflect user interaction with a website

A given user can interact in multiple ways with a website. Let's simplify a bit and say say a user can: Post a message Comment a message "like" something on the website via Facebook (after that we ...
1
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1answer
134 views

problem constructing an equation that connects variables

need a suggestion/advice/inputs from the mathematicians here. I have collected data of number of instructions/sec executed by a processor every second, number of loads/stores performed every second ...