# Questions tagged [data-analysis]

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.

700 questions
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### Interpolation on curvilinear grid

How could someone interpolate spatial data on a curvilinear grid, like the one in the picture shown?
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### Similarity between observations and an ideal trend

I have a series of well known data showing, for example, the average weight by age in Europe. Let's say yesterday I called a lot of people and I asked for their age and weight. The data coming from ...
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### How can I make a best fit line out of data where each point is weighted more heavily than the previous?

I'm thinking that there should be a linear regression technique that allows me to value recent data more that older data. (Maybe this difference in weight could be configurable through a constant). ...
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### longitudinal study with repeated measures

I have a data-set which is collected using two devices (A and B) to measure the same variable, for 10 participants during 5 different types of activities . Each activity goes for 15 minutes and there ...
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### Sample mean and sample covariance canonical forms

Let $(x_1, x_2,\dotsc, x_n)$ be a sequence of vectors: ($\forall i=1,\dots,n$) \begin{pmatrix} x_i^1 \\ x_i^2\\ \vdots\\ x_i^m \end{pmatrix} In statistics, one often has to compute the ...
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### In Support-Vector-Machine, why is the hyperplane given by $(p-1)$ dimensions?

In SVM, each feature vector is viewed as a data point in a $p$-dimensional plane and different labels are separated by a $(p-1)$ dimensional hyperplane. Please see the wikipedia entry: https://en....
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### Understanding the lower and upper limit of a graph

I was recently presented the following graph: I was given very little context and I have to recreate it. I don't want it to be done for me, but some context would help. Any idea what these upper and ...
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### Modeling distributed densities or is it?

Lets say that I am counting pixels over time. Each pixel is either the color red or blue. Let's say that I make up some threshold for the number of red pixels that I count and that when I reach this ...
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### Compare Two Values - Stardew Valley Food

In the game, Stardew Valley, you can pick up items through farming, fishing, foraging, cooking, etc. Most tasks use up your character's energy, such as swinging an ...
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### Are there 'serious' mathematical problems emerging from data science?

Are there any proper research-level mathematics problems that have come out of the activity known as "data science"? I put the quotes because it really is not so clear what "data science" is to me; I ...
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### Finding Objects Most Similar to Other Objects as a “Linear Combination”

I have a small collection of objects, $\{o_i\}_{i=1}^{20},$ that have several properties (all quantitative, or can be made to be quantitative) that differ among themselves. So $o_1$ has, say, $10$ ...
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### What Conclusions Can I Draw from Percentiles About my Set of Data?

I have a specific survey question that I am analyzing for the topic Should High Schools Implement a Uniform Policy?. I am supposed to create biased survey questions ...
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### Best Average to Represent Quantitative Data?

For a final assignment, my two group members and I have created a biased survey called Should Public Schools Implement a Uniform Policy? We have about 2-3 ...
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### What Can Median Tell Me About my Data?

For a final assignment for math, I was required to take the "Yes!" side of 'Should Uniforms Be Implemented at School?' My job was to create a biased survey that would make people agree with our side ...
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### How to fit Poission distribution with large mean?

I have one set of discrete data plotted below. I suspect the data follows Poisson distribution with mean $\mu \simeq 400$ and standard deviation $\sigma \simeq \sqrt{400} = 20$.  n(k) = \frac{\mu ^...
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### Is there any exact definition for “imbalanced datasets” or “imbalanced learning”?

What is the exact definition for "imbalanced datasets" or "imbalanced learning"? Some article states it as, In such problems, almost all the instances are labeled as one class, while far fewer ...
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### Where to start learning about topological data analysis?

I was wondering if anyone could help me out with finding a nice introductory introductory text for topological data analysis (I'm speaking as somebody who has two semesters of experience with topology,...
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### Removing noise when the signal is not smooth

Suppose we have (an interval of) a time series of measurements: We assume it can be explained as a "simple" underlying signal overlaid by noise. I'm interested in finding a good algorithm to estimate ...