Recently, the CDF experiment at the Fermilab Tevatron has
used complementary methods to make multiple measurements of the singly
produced top quark cross section.  All analyses use the same dataset with
more than 2 fb-1 of CDF data and event selection based on W + 2 or W + 3
jet events with at least one b-tagged jet.  However, due to differences
in analysis techniques these results are not fully correlated and a
combination provides improved experimental precision.  Two independent
methods are used to combine the results.  This combination results in
an improved measurement of the single top production cross section and
also the CKM matrix element V_tb.