Should our function in 1B take a value for sigma as well, since we
are trying to optimize our log likelihood function of beta *and*
sigma? If no, how does one get the value of sigma that you need to
calculate the log likelihood?
Just concerned because it mentions our log likelihood taking a beta,
but not a sigma. (Also, if it is yet another parameter to throw into
the function, how does one optim over two variables?)
~Meryl