In empirical studies of friendship networks participants are typically asked, in interviews or questionnaires, to identify some or all of their close friends, resulting in a directed network in which friendships can, and often do, run in only one direction between a pair of individuals. Here we analyze a large collection of such networks representing friendships among students at US high and junior-high schools and show that the pattern of unreciprocated friendships is far from random. In every network, without exception, we find that there exists a ranking of participants, from low to high, such that almost all unreciprocated friendships consist of a lower-ranked individual claiming friendship with a higher-ranked one. We present a maximum-likelihood method for deducing such rankings from observed network data and conjecture that the rankings produced reflect a measure of social status. We note in particular that reciprocated and unreciprocated friendships obey different statistics, suggesting different formation processes, and that rankings are correlated with other characteristics of the participants that are traditionally associated with status, such as age and overall popularity as measured by total number of friends.

Simply Statistics: Interview With Joe Blitzstein

simplystatistics:

Joe Blitzstein
Joe Blitzstein is Professor of the Practice in Statistics at Harvard University and co-director of the graduate program. He moved to Harvard after obtaining his Ph.D. with Persi Diaconis at Stanford University. Since joining the faculty at Harvard, he has been…

Interesting interview about statistics and data science. 

the-star-stuff:

Geeky Math Equation Creates Beautiful 3-D World

This article was published by Wired on December 9, 2009. This is not a new news but I still find it amazing. The first time I saw this, I was like, “WHOOAAH! These are beautiful!”  

This article was about the Mandelbulb. A group of math geeks created a three-dimensional analogue for the mesmerizing Mandelbrot fractal. The 3-D renderings were generated by applying an iterative algorithm to a sphere. The same calculation is applied over and over to the sphere’s points in three dimensions. In spirit, that’s similar to how the original 2-D Mandelbrot set generates its infinite and self-repeating complexity.