As you lack data in the middle of the range, the results you obtain will
apply only to the regions for which you have data.
You will require an estimate of the variance of A. To obtain this
estimate, you will need to take at least two measurements using A for at
least one case.
You will then need to use Deming Regression to relate the two methods.
Phillip Good
Common Errors in Statistics (and How to Avoid Them)
-------- Original Message --------
Subject: [SPAM] Assessing accuracy of a measurement method
From: Jonathan James <[log in to unmask]>
Date: Tue, July 13, 2010 7:02 am
To: [log in to unmask]
Hello,
this is my first mail to allstat (although I have been reading the
archives for
a while)
I have been asked to assess the accuracy and precision of a new
measurement
method (Let's call it method B). This new method is compared to an
existing
one (A) that is considered to be "very accurage" and has its own
specifications
in terms of stdev of a single measurement. What we do is to measure
several
samples with method A and then with method B. Since A is very expensive,
only
one A measurement per case is available. Method B is cheaper, so we
measure
each sample with method B between 10 and 30 times. Another problem is
that we
are unable to find samples that would span across the entire legal
measurement
range, resulting in several samples in the first quartile of the range,
several
in the last range quartile and almost no in between.
How can I assess the accuracy and precision of method B? Any help or
link will
be appreciated.
Thank you very much
Jonathan James
P.S. This is not a homework.
P.P.S I admit, I don't know statistics well
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