Jacco,
I/sigma_I is a good idea in principle. It just looks ugly if you get the
sigmas right for certain instruments - there are meaningless steps all
over the place.
All of these problems of "what to plot" would go away if we all
submitted powderCIF files for our refinements. The "plot" could then be
an interactive application embedded in the electronic document and
readers could select the units they want. They could also zoom in on it.
It is hard to get away without a cif for a single crystal structure now
- just make it so for powders too.
Didn't a physicist already get caught faking results by leaving embedded
plots in submitted documents?
Is it just time to formalise that plots should embed the table of
numbers they represent? When the next generation of CIF arrives (DDL3) I
understood it will be possible to describe the equation linking 2theta
to Q for example. This could keep Klaus happy, as well as the thousands
of people using CuKa in the lab.
Jon
Jacco van de Streek wrote:
--- "Von Dreele, Robert B." <[EMAIL PROTECTED]> wrote:
Actually, I looked at Luca's little "show" & was
sufficiently interested
that GSAS will now plot sqrt(I) style plots. There
is one "problem" -
the value of "I" can be negative particularly after
a background
subtraction. These must be suppressed to zero for
this plot to work -
thus there is a small risk of something getting
hidden.
I think that that is because although it is called a
SQRT plot, that is just because that is how it is
usually implemented. What is meant is a more general
principle, namely that of displaying the data points
divided by their ESDs (where, of course, the ESDs must
be calculated *from the raw number of counts*). I will
try to explain why.
