Talk:Directional statistics

From Wikipedia, the free encyclopedia

This article is within the scope of WikiProject Statistics, which collaborates to improve Wikipedia's coverage of statistics. If you would like to participate, please visit the project page.

The final step of the formula given for the example is unclear; apparently it is written for result in radians. Wouldn't it be better written this way:

Mean angle = arctangent (mean sine / mean cosine). If mean cosine < 0, add 180 degrees to the result. If mean sine <0 and mean cosine >= 0, add 360 degrees to the result.

Jim

[edit] Modulus method

The modulus method only works in few specific cases (such as the example given).

Consider the same example but rotated further to the left so that the three angles are 330, 340 and 350 degrees. Taking the modulus 360 of the sum (1020) results in 2 remainder 280, which divided by 3 is clearly not 340.

As the remainder (in a modulus 360 operation) can only range from 0 to 360, the 'average' can only range from 0 to 360/n.

Unless I'm misunderstanding the procedure, I would suggest taking it out.

Fink3412 09:28, 20 August 2007 (UTC)

Agreed - I've removed it. Also, this article is about Directional statistics itself, not about various methods to calculate a circular average. Tomixdf 09:42, 20 August 2007 (UTC)