Humankind's earliest efforts at observations can arguably be considered the harbingers of science―and its principles and methods. Until very recently, contemporary science―and scientists―held that routine monitoring (observations and measurements) could not be considered rightly as science. This likely was due to the notion that the practical, often operational, nature of monitoring was not considered to fit neatly within prevailing ideas of basic, hypothesis-driven, science. This view has changed substantially with the establishment of programs to explore, define and validate scientifically-defensible monitoring, observation and measurement activities. For example, the Environmental Monitoring and Assessment Program (EMAP), over the past 20 years has strengthened the science of monitoring. It has done this by investigating how monitoring can generate data and other information along with an understanding of the probability-based confidence that accompanies that data and information.

(cited from:
The Encyclopedia of Earth,
http://www.eoearth.org/article/Monitoring
October 4th 2010)