Using the Lorenz equations, we have investigated whether unstable peri
odic orbits (UPOs) associated with a strange attractor may predict the
occurrence of the robust sharp peaks in histograms of some experiment
al chaotic time series. Histograms with sharp peaks occur for the Lore
nz parameter value r = 60.0 but not for r = 28.0, and the sharp peaks
for r = 60.0 do not correspond to a histogram derived from any single
UFO. However, we show that histograms derived from the time series of
a non-Axiom-A chaotic system can be accurately predicted by an escape-
time weighting of UFO histograms. [S0031-9007(98)07397-9].