The results for 1956 are shown in Table I. The
results for 1957 are shown in Table II. Except
for the Cape May fewer observations were taken
than in 1956. By means of the sign test (Wilson, 1952),
treating each observation irrespective of the num
ber of flights as a single estimate of mean interval
between flights, a test of the difference in activity
can be performed. These data are summarized in
the following inequality, where is interpreted
to mean "has smaller mean interval between
flights, with 95ro certainty.