Joe writes
I am taking a lab now. Like a robot I want
to quote the uncertainties in my uncertainties, but I have been
explictly told not to do this. They will take points off to
discourage me. And yet, if I quote measurements without any
uncertainties, they'll give me a zero.

Er, technically aren't error bars just a useful guide to the likely
range of 'real' values.

Usually error bars cover two standard deviations (95% confidence) but
you can of course select any confidence limit you like. If you wanted to
be **really** sure then you could chose error bars based on 99.9999%
confidence limit (but you probably ought to mention this somewhere on
the chart).

I actually have a bit of a gripe about this and 'significant'.

In agriculture the uncontrollable variations are so immense that its
quite common to find that whole series of trials produce nothing
'significant'. This is often despite some very large differences between
the averages of (replicated) trials. I once got hold of the actual plot
data on one (important) trial and found that one particular treatment
was significant at the 82% level. Roughly this means there was a 1 in 5
chance that the (big) difference was actual. For a farmer, using a
treatment that pays 4 out of 5 times is a 'chance well worth taking',
and VERY significant. Heck, you can't predict yields (even in the UK) to
better than 20% with a 50-50 confidence.

Equally if you are in the pharmaceutical industry, to say that a product
is 'safe' with 95% confidence might (just) not be adequate. It would be
very sad for the product to kill 4% of those taking it, or even to kill
1%!

--
Oz
This post is worth absolutely nothing and is probably fallacious.

Use functions].
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