  Chemical analyses of raw materials are often repeated in duplicate or
triplicate. The assay values obtained are then combined using a predetermined
formula to obtain an estimate of the true value of the material of interest.
When duplicate observations are obtained, their average typically serves as an
estimate of the true value. On the other hand, the "best of three" method
involves taking three measurements and using the average of the two closest
ones as estimate of the true value.
  In this paper, we consider another method which potentially involves three
measurements. Initially two measurements are obtained and if their difference
is sufficiently small, their average is taken as estimate of the true value.
However, if the difference is too large then a third independent measurement is
obtained. The estimator is then defined as the average between the third
observation and the one among the first two which is closest to it.
  Our focus in the paper is the conditional distribution of the estimate in
cases where the initial difference is too large. We find that the conditional
distributions are markedly different under the assumption of a normal
distribution and a Laplace distribution.
