  The simplest observables used to probe the interaction of hard partons with a
QCD medium in ultrarelativistic heavy ion collisions measure disappearance,
such as the nuclear modification factor R_AA. The information content of such
observables is however limited. More differential information is obtained from
triggered correlation observables where a trigger condition ensures that a hard
event has taken place and the correlation of other objects in the event with
the trigger contains information about the nature of parton-medium interaction.
By construction, triggered correlation observables are conditional
probabilities, i.e. they measure events biased by the trigger condition. The
presence of this bias makes the interpretation of observables non-intuitive,
but at the same time represents an opportunity to design future measurements to
selectively probe particular physics. In this work, an overview over the four
types of biases occuring in triggered hard correlation observables is given,
followed by a study of current jet correlation phenomenology in the light of
the preceding discussion.
