Date: Thu, 31 Aug 2000 11:14:28 -0400

Author: Machele Bailey

Subject: Re: Excel


It does help! It shows me that this is just as bad as the lab I've got!
There's no way it will work for the first lab of the introductory labs. So
let me ask another question...

Does anyone have a simple, but decent error analysis lab they do for INTRO
labs? Right now, ours are pretty algebra intensive and it scares the heck out
of our students...I'd like to replace it with something a little more
elegant. Any ideas?


Andy Dougherty wrote:

> On Thu, 31 Aug 2000, Machele Bailey wrote:
> > Does anyone happen to have a good procedure for doing a gaussian fit on
> > histogram data in excel? I thought I'd ask before I re-invent the
> > wheel...
> For a sophomore-level class, I used the Solver Add-in. It was a sort of
> computer-assisted manual curve-fitting, but it was appropriate for that
> course.
> Briefly, the way it works is as follows: (I can probably dig up the
> write-up if needed.)
> You set up a few cells to contain the desired fitting constants
> (overall amplitude, mean, and width of the distribution). Then
> set up a formula column that computes the "fitted" function. Have the
> students make a graph that shows both the raw data and the "fitted"
> function.
> Next, create a "differences squared" column and, finally, a ChiSq cell
> that contains the sum of all the square differences (normalized, if you
> wish).
> Students should be encouraged to manually fiddle with the different
> fitting parameters to see what they do and to get a decent first guess.
> When you run Solver, you give it a goal of minimizing ChiSq by
> manipulating the fitting cells.
> (Sorry to be vague about the exact terms. My working copy of Excel is in
> the lab several buildings away at the moment.)
> For a class less-interested in curve-fitting gory details, you could
> easily supply a template .XLS file with all the stuff filled in and they
> would just have to run Solver.
> Hope this helps. Let me know if you want more precise details.
> --
> Andy Dougherty
> Dept. of Physics
> Lafayette College, Easton PA 18042

Machele Bailey-----Lab Manager-----Wake Forest University

-----"Nothing shocks me. I'm a scientist." - Indiana Jones-----