Can anyone please tell about slope function

WS via (by novalidaddress from
Wed Mar 23 10:56:18 EST 2011

Dear Jay,

I think you got me a bit wrong. This was not an attempt to subverse
the presentation of measured data by using "politically incorrect"
As those colorimetric assays usually are not supposed to be a thesis
of itself, one usually is interested in quick and accurate results
(actually, protein determinations are quite annoying to me).
Spreadsheets like excel provide some quick and easy means to reach
that goal and it's easy to set up forms where you just enter your data
and you get the results you need for your actual experiment.

Drawing a regression curve allows to display the corresponding
function. Regardless if you want linear or polynomic regression, if
you plot the diagram in the canonical way (y-axis: OD, x-axis:
concentration), you will have to do additional mathematics to obtain
an equation that allows you to calculate concentrations from ODs. When
you do it as I suggested (x: OD, y: conc), excel will give you
directly an equation you may use immediately for downstream
calculations (just copy the coefficients into the spreadsheet). You
simply don't need to calculate the inverse function by yourself which
costs time and may introduce errors in such a routine task (and might
become quite difficult if the regression is not linear). Of course,
one should understand what one is doing and not just enter some
figures into a spreadsheet you snatched from your (colleague who
snatched it from his)^n. Or your PI told you to enter the data into
that form and you actually have no idea what's happening.

I also would not blame Sudheer for asking his question. It shows there
might be some profound deficits in the concurrent education of
students and young scientists. Probably the focus gets more and more
on reproducing knowledge and being fast (in order to get good
gradations, scholarships, grants, good jobs, etc etc) instead of
understanding what really happens and being able to dissect and
analyze problems and to get your feet on the ground in unknown


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