There are several parameters to measure the effect of retrieval: recall factor, pertinency factor, omission factor,
noise factor, and so on. The relation between recall factor and pertinency factor is opposite interdependently, namely,
to increase the recall factor would reduce the pertinency factor, and vice versa. For information retrieval, the most
important factor to affect quality of the retrieval is the omission factor, then, it must be reduced to a minimum.
Noise detection will reduce the efficiency of retrieval and also affect the quality of retrieval. Therefore, we must strive
to overcome the incorrect detection and avoid false detection, or to improve recall factor and pertinency factor.