  The relations between star formation and properties of molecular clouds are
studied based on a sample of star forming regions in the Galactic Plane.
Sources were selected by having radio recombination lines to provide
identification of associated molecular clouds and dense clumps. Radio continuum
and mid-infrared emission were used to determine star formation rates, while
13CO and submillimeter dust continuum emission were used to obtain masses of
molecular and dense gas, respectively. We test whether total molecular gas or
dense gas provides the best predictor of star formation rate. We also test two
specific theoretical models, one relying on the molecular mass divided by the
free-fall time, the other using the free-fall time divided by the crossing
time. Neither is supported by the data. The data are also compared to those
from nearby star forming regions and extragalactic data. The star formation
"efficiency," defined as star formation rate divided by mass, spreads over a
large range when the mass refers to molecular gas; the standard deviation of
the log of the efficiency decreases by a factor of three when the mass of
relatively dense molecular gas is used rather than the mass of all the
molecular gas.
