The earth's temperature (which affects seed germination, crop
survival in bad weather, and many other aspects of agricultural
production) can be measured using either ground-based sensors or
infrared-sensing devices mounted in aircraft or space satellites.
Ground-based sensoring is tedious, requiring many replications to
obtain an accurate estimate of ground temperature. On the other
hand, airplane or satellite sensoring of infrared waves appears to
introduce a bias in the temperature readings. To determine the
bias, readings were obtained at five different...