Content by James Beagle III, Donald J. Wheeler
When Are Instruments Equivalent? Part 3Comparisons using multiple standards
Mon, 06/10/2019 - 12:03
In Parts One and Two we defined the equivalence of instruments in terms of bias and measurement error based on studies using a single standard. Here we look at comparing instruments for differences in bias or differences in measurement error while…
When Are Instruments Equivalent? Part 2Do the instruments have the same amount of measurement error?
Mon, 05/06/2019 - 12:03
Last month we provided an operational definition of when measurement systems are equivalent in terms of bias. Here we will look at comparing the within-instrument measurement error between two or more systems. Once again we must emphasize that it…
When Are Instruments Equivalent? Part 1Practical answers to an age-old question
Mon, 04/08/2019 - 12:03
As soon as we have two or more instruments for measuring the same property the question of equivalence raises its head. This paper provides an operational definition of when two or more instruments are equivalent in practice.  Churchill Eisenhart,…
Is That Last Digit Really Significant?You no longer need to guess
Mon, 02/05/2018 - 12:03
Whenever we make a measurement, we have to decide how many digits to record. Traditional answers for this question are often little more than guesswork glorified by time. And with digital readouts, are all the displayed digits real? This column…
ANOX: The Analysis of Individual ValuesA new test for homogeneity
Tue, 09/05/2017 - 12:03
Sometimes we use a chart for individual values and a moving range (an XmR chart) to assess the homogeneity of a finite data set. Since this is an "off-label" use for the XmR chart, we first consider the drawbacks associated with using a sequential…