Calibration consists of using a fitted regression line to estimate the
value of an unobserved independent variable x corresponding to an obs
erved dependent variable y. To construct a confidence interval for a s
ingle x, Eisenhart introduced a procedure that consists of inverting p
rediction intervals around the regression line. Numerous other inferen
ce procedures have been proposed for multiple-use calibration, in whic
h a single fitted regression line is used repeatedly to estimate many
x's. We provide a synthesis of this literature and offer some numerica
l comparisons. We also attempt to motivate the use of various criteria
based on the particular points of view of the various parties involve
d in determining the calibration or using the results. In addition, we
derive probability expressions for computing exact simultaneous predi
ction intervals that enable the construction of tighter limits than ar
e currently available based on that criterion.