Formula for "old" degrees of freedom

[ghonerka]

Thank you Dr. van Buuren for your excellent book!

The first equation in Section 2.3.6 gives the "old" degrees of freedom from Rubin 1987. I believe
(m-1)\left(1+\frac{1}{r^2}\right) should be changed to (m-1)\left(1+\frac{1}{r}\right)^2.

Best,
Gordon Honerkamp-Smith