Re: bias and variance  definition of g bar
I'm having doubts about the variance value in example 2.8 since it indicates that the root mean square deviation of the test data from the sinusoid line is 1.3= sqrt(1.69). So the magnitude of the average (a*x+b) difference from (a_mean*x+b_mean) evaluated at a given point on the sinusoid is bigger than the root mean square value (.7071) of the sinusoid that generated the data point in the first place? I'm inclined to doubt that.
The mean square deviation between the slope of each generated line and a_mean is larger than 1.69 so at this point I have no idea where that variance number came from.
