Calculating the power spectral density


#1

I am working on using data collected by Muse to calculate focus level of a user. The formula is focus level= beta/ (alpha+theta). I think I need to get the power spectral density value of beta, alpha and theta wave. Can I just use the absolute band powers to calculate the power spectral density? If so, then what is the base number of the logarithm calculation? 10 or e?