Different endeavors have been made to deliver a scientific categorization of levels of estimation. The psychophysicist Stanley Smith Stevens characterized ostensibly, ordinal, stretch, and proportion scales. Ostensibly estimations don't have significant position request among values, and license any balanced (injective) change. Ordinal estimations have loose contrasts between back to back values, yet have a significant request to those values, and license any request saving change. Stretch estimations have significant distances between estimations characterized, however the zero worth is inconsistent (as for the situation with longitude and temperature estimations in Celsius or Fahrenheit), and license any direct change. Proportion estimations have both a significant zero worth and the distances between various estimations characterized, and license any rescaling change