Confidence Intervals from the Rayleigh Test http://adsabs.harvard.edu/full/1994MNRAS.268..709B
MATLAB code for circ_rtest function. http://www.mathworks.com/matlabcentral/fileexchange/10676-circular-statistics-toolbox--directional-statistics-/content//circ_rtest.m
Lecture on directional statistics. http://webspace.ship.edu/pgmarr/Geo441/Lectures/Lec%2016%20-%20Directional%20Statistics.pdf