---> F-measure is defined as a harmonic mean of precision and recall,.
---> The harmonic mean is more reasonable than the arithmetic mean when computing a mean of ratios.
---> All search algorithms have to make a tradeoff between recall and precision.
---> Typical web surfers would like every result on the first page to be relevant (high precision). ---> In contrast, various professional searchers such as paralegals and intelligence analysts are very concerned with trying to get as high recall as possible.
-Aamir
