[ RadSafe ] Comparison of a Measured Result to the Critical/Decision Level

Cindy Bloom radbloom at comcast.net
Wed Mar 4 06:47:53 CST 2009


My opinion is no, but this assumes that the data used to calculate the (a 
priori) critical and decision levels are representative.  That means it's 
important to assure that background and efficiency checks are not 
fluctuating outside predetermined acceptable levels.  The determination of 
the critical level includes consideration of expected fluctuations in the 
measurement system, as well as a predetermined acceptance level of false 
negative and false positive measurements.


At 07:13 AM 3/4/2009 -0500, Redmond, Randy (RXQ) wrote:
>Question for the group
>When comparing a measured result to the critical/decision level, should 
>the error (2-sigma) associated with the measured result be added to the 
>measured result prior to comparison?  For example:
>(all values in dpm and were fabricated)
>MDA: 0.30
>Lc: 0.16
>Result: 0.10
>2-Sigma Error: +- 0.07
>Should the error be added to the result prior to comparison to the 
>critical level?
>Thank you,
>Randy Redmond
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