From | David Airey <[email protected]> |
To | [email protected] |
Subject | re: st: Checking reliability of a measurement device |
Date | Fri, 26 Nov 2004 09:55:56 -0600 |
That is interesting.Hi Statalisters, a Dentistry PhD student did some measurements on 12 teeth with varying conditions and he asked me how could he show that the device used for the measurements is reliable. More specifically each one of the 12 teeth has been measured by this device by 2 raters (a and b) X 2 time points (week 1 and week 2) X 6 relative positions = 24 measurements. The goal is to show that the discrepancies among measurements are not statistically significant.
My first thought was to use a 2-level model (measurements nested within tooth) and test the rater, time, position effects and maybe their interractions. Something like xi:xtreg length i.rater i.time i.position,i(tooth) assuming that a random intercept structure is adequate for this experiment. The problem is that this is the first time I deal with a problem where the goal is to "prove" that some factors have no significant effects, thus I am not very confident with the aforementioned method. Any thoughts? Nikos Pantazis Biostatistician
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