  We discuss the conditions for an effective field theory (EFT) to give an
adequate low-energy description of an underlying physics beyond the Standard
Model (SM). Starting from the EFT where the SM is extended by dimension-6
operators, experimental data can be used without further assumptions to measure
(or set limits on) the EFT parameters. The interpretation of these results
requires instead a set of broad assumptions (e.g. power counting rules) on the
UV dynamics. This allows one to establish, in a bottom-up approach, the
validity range of the EFT description, and to assess the error associated with
the truncation of the EFT series. We give a practical prescription on how
experimental results could be reported, so that they admit a maximally broad
range of theoretical interpretations. Namely, the experimental constraints on
dimension-6 operators should be reported as functions of the kinematic
variables that set the relevant energy scale of the studied process. This is
especially important for hadron collider experiments where collisions probe a
wide range of energy scales.
