  While quark-hadron duality is well-established experimentally, the current
theoretical understanding of this important phenomenon is quite limited. To
expose the essential features of the dynamics behind duality, we use a simple
model in which the hadronic spectrum is dominated by narrow resonances made of
valence quarks. We qualitatively reproduce the features of duality as seen in
electron scattering data within our model. We show that in order to observe
duality, it is essential to use the appropriate scaling variable and scaling
function. In addition to its great intrinsic interest in connecting the
quark-gluon and hadronic pictures, an understanding of quark-hadron duality
could lead to important benefits in extending the applicability of scaling into
previously inaccessible regions.
