Weibull Probability Density Function in Excel

Uploaded by PSUwind on 23.07.2012

I'm going to show you how to use
the Weibull function in Excel.
So here I've got a sheet already started where I've got
velocities listed in column A ranging from 0 to 25 m/s.
Notice I have 1 m/s bins,
therefore in this case I could have 1/2 m/s - 2 m/s,
depends on what your looking for. You can also use mph.
So I'm going to type in now the Weibull function
which if I start to spell it out you'll see Excel
starts to recognize what I'm trying to look for, continue
to type it in and now it's asking for an X, X is the
velocity in our case. So you're going to refer back
to cell A2. Alpha, if you look in the help
file you'll find that this is the shape factor.
And we're just going to use a simple case of
Rayleigh distribution, it needs a of 2 there,
that's what we usually know as k.
Beta is what we know as lambda,
and we're going to use 7. And then it's asking whether we
want a cumulative function or not. If we do you do true and
typically we're not going to do that, we're going to do false,
because we are looking for density function.
Okay, so for zero you're getting zero, but to
copy this down, I'm just going to double click here, and
you can see the whole range of values. If you were to
sum this column it should get pretty close to 1.
If you've done it wrong and you've mixed up your alpha
and your beta you won't see all these numbers, you'll
see only a few numbers in the first few columns, so you
can test that out. And the other thing you can do is plot it
and it looks like what we are expecting as a Weibull curve.