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September 4

What exactly is a "Gaussian blob" chart, and in what situations is it used?

In This page, showing how to use a Java library that does charts, there is "ScatterChart01: Gaussian Blob", which shows an image of small circles with a radius. What is this exactly and where is it used? The example code shows a call to Random.nextGaussian, which i never heard of before.

I acknowledge partly that this may just be a "normal" scatter plot, since the dots seem to be all of the same radius. Googling for "Gaussian Blob" only returns Blob detection as defined in computer science, which is something about graphical areas that look similar or share characteristics. Is this chart called Gaussian Blob only because it resembles one such blob with all its data points? I HAVE also seen charts like this with different sized dots. If my suspicion is right and this is just a scatter plot, what is the use in different radius dots? What does it mean and what are some applications?

216.173.144.188 (talk) 20:01, 5 September 2014 (UTC)[reply]

This is a normal scatterplot of points sampled from a two-dimensional Gaussian probability distribution. Blob is an informal term; the points tend to form a mass or blob centered on the origin. --Mark viking (talk) 20:06, 5 September 2014 (UTC)[reply]

Thank you for that clarification. I think the chart I was thinking of in the second part of my original post was Bubble chart. Are there any really good examples for why this type of chart would be used? Is there a situation where the size of the dot shows something intuitive, or is it just used to hold a 3rd dimension of data?

216.173.144.188 (talk) 20:19, 5 September 2014 (UTC)[reply]

Even in this page which seems to try to explain the reason for bubble charts, and has examples, it seems the third variable is not given special properties above x and y, the data for this radius variable could be whatever you wanted, just like X and Y. Am i correct in assuming Bubble Charts exist because "3D Scatter Plots" would be insane to try to look at and make sense of?

216.173.144.188 (talk) 20:45, 5 September 2014 (UTC)[reply]

A regular bubble chart doesn't seem as useful to me as a geographic bubble map. For example, a map of the US could have different sized blobs indicating the populations of cites, or the magnitudes of earthquakes. StuRat (talk) 23:57, 5 September 2014 (UTC)[reply]