[Physltest] [Phys-L] Re: loggerpro question on video analysis

[Bernard Cleyet <anngeorg@PACBELL.NET>]

Yes, principle exception is w/ the Rad. detector.  I collect w/ LP and
export the data to Kaleidograph.  I may have posted this:  I use the
solvent partition method developed by the Chemists at U. Washington
(Used by their Phys dept. I found a German U. that does it also, and
it's discussed in Nuclear Chem. texts).  It's more convenient than the
Cs -- Ba  ion exchange method.

bc

p.s. I just discovered that LP is most of the way there, i.e. the error
bars may be generated from a calculated column.  In this case the sqrt
of the counts column.  A quick read of Peter Scott's * description of
his Marquardt NLLS fit program indicates use of the variances of the
data is required, so I think it should be a simple matter to input them
into LP?

*  For UCSC Physics Advanced Lab.

John Gastineau wrote:

> Bernard Cleyet wrote:
>
> > "... just tilt the camera"
> >
> > Haah!
> >
> > and I was going to suggest rotating the axes by using additional data
> > columns w/ trig. fcn. multipliers.
> >
> > bc, rather stupid.
> >
> > p.s. I was going to suggest calling Vernier w/ that suggestion,  [I've
> > found them very friendly and helpful -- still not too big a company.]
> > but John (w/ whom I've spoken) beat me to it.
> >
> > p.p.s. however, unless I'm missing something their Chi Square does not
> > make use of the error bars.  Perhaps Mr. (Dr.?) G. will inform us.
> That's right--the curve fitting routines of Logger Pro (any version)
> do not make use of error bars. All points are equally weighted. For
> sensor or video analysis data, this choice is usually appropriate.
> There are times that weighted fits are appropriate, but at present our
> software doesn't offer that feature.
>
> And yes, it's Dr. I've been a participant on phys-l since 1989. When I
> was teaching I posted here a lot, but since coming to Vernier I tend
> to speak only when spoken to, for fear of folks complaining of
> commercial posting. I'll go back to my corner now...
>
> JG
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