In 1989, as Cold War tensions relaxed, Soviet scientists for the
first time published data about nuclear weapons tests conducted during
1961-1972 at sites in Soviet Central Asia.  Western scientists had previously
estimated the size of the explosions from their seismic magnitudes.
Publication of the Soviet data provided an opportunity to check the accuracy
of Western magnitude estimates.  The dataset called ``soviet.dat" gives 
the dates, magnitude estimates and reported yields for 19 of these tests.
(Data is from Vergino, Eileen S. (1989).  ``Soviet test yields."  EOS
Transactions, American Geophysical Union, 70:1511.)

Variables are:

       date
       estimate
       yield