[ RadSafe ] Clarification : Validity / Usefulness . . .

[Pete_Bailey at fpl.com]

Thanks to all that have responded....

I'm not after guidance on sampling frequency
or testing if two positive measurements are different . . .

What I'm after (and many spoke around ,but didn't directly answer):

In your world i.e., by your procedures
would you consider any one of the following
different pairs of R +-r  to be 'not useable'  for
comparison to whatever ( a limit, a prior sample, etc) ?

a.    110  +- 140

b.    480 +- 140

c.     270 +- 140

d.    630 +- 140

If your procedure would have you consider
a pair as 'not useable', what is the
basis of your procedure's decision process ?

As far as 'difference' of two positive results,
I am very much aware of, familiar with,
the "z score" , "zeta test"; it is standard stats.

BUT "by your procedures", what do you do when
one of the two is  "less than (a number) " and you
don't have a standard deviation of the LLD value
and the other is  R +-r   ( with R not being far from a typical LLD value)?
  - do you use the "z score test" & assume  r  to be applicable to the LLD
value ?

Hopefully, the above clarifies what I was attempting to ask yesterday....