Before entering fully into the meaning of the term normal curve, it is necessary to proceed to discover the etymological origin of the two words that give it shape:
-Curve is a word that derives from Latin, exactly from “curvus” which can be translated as “curved”.
-Normal, on the other hand, also comes from Latin. In his case, it is the result of the sum of two perfectly defined components: the noun “norm”, which is synonymous with “rule” or “model”, and the suffix “-al”, which is used to indicate “belonging” or “relationship”.
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A curve is that which departs continuously from the straight direction, but without creating angles. The line used to graphically represent the magnitude of a phenomenon according to the values of one of its variables is also called a curve. Normal, meanwhile, is what is natural or works as a rule.
These ideas can help us understand what a normal curve is, although the concept has a specific use in the field of statistics. The normal curve is called the Gaussian distribution : the probability distribution of a continuous variable that is usually close to a real phenomenon.
The use of a normal model allows us to assume that the observations derive from the sum of independent causes. The normal curve, in this framework, serves to model social and natural phenomena in an approximate way to reality.
The graphical representation of the normal curve is known as a Gaussian curve. This bell-shaped line is symmetric with respect to a certain parameter : there is a concave middle zone, which has the mean value of the function in the center, and two convex extremes that tend to approach the X axis. The Gaussian distribution, therefore, shows the most frequent values in the center of the bell, leaving the least frequent at the extremes.
Take the case of the average height of men between the ages of 18 and 60 born in a certain region. Although in this group there are people who are 1.45 meters tall and others who are 2.05 meters tall, most of the subjects are between 1.65 and 1.85 meters tall. The normal curve will cause these more common values to be reflected in the center of the bell curve.
In the same way, in addition to all that has been exposed, we cannot overlook the fact that there are other series of relevant aspects about the normal curve that are worth knowing. We are referring to the following:
-It allows not only to “model” what are social or natural phenomena but also others of a psychological nature.
-In the eighteenth century is where the origin of the curve or normal distribution. Specifically, it appeared in 1733 in an article written by the French mathematician Abraham de Moivre, who has become a benchmark in statistics for the contributions he made to the theory of probability. However, after him it would be perfected by other figures such as Adrien-Maire Legendre or Johann Carl Friedrich Gauss.
-His name as such was given years later. Specifically, it was awarded in 1875 by characters such as Francis Galton, Charles S. Peirce and Wilhem Lexis.