Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I've read journal "On the Comparison of Several Mean Values: An Alternative approach" (Welch, 1951). I don't understand this expression: $$E\left(\exp\left[ \sum_t ( w_t - \omega_t ) D_t\right]\right),$$

where $$D_t^r = \left(\frac{\partial^r}{\partial z_t^r}\right)_{z=\omega} $$ and $E$ is expectation over $w_t$

Why is $D_t$ written in the last equation?

share|cite|improve this question
What kind of mathematical objects want $r,t,w,\omega$ denote? We can have some guesses, but please specify them a bit. – Berci Nov 30 '12 at 11:05
For more explanation, you can read this journal:… – Maifiana Sari Dec 4 '12 at 5:28

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.