6. Normal Distribution (NPC)


It refers to the graphical representation of a normal distribution of a continuous variable like IQ , weight etc .Parametric statistics( follows a set of assumptions )need require the data to be normally distributed .

Normal Probability Curve ( NPC)


  • It is bell- shaped and has a single peak at its center .
  • It extends from minus infinity to plus infinity.
  • The curve is asymptotic that is it doesn’t touch the baseline . The mean is the starting point for working with the normal curve.
  • It is symmetrical that is divided into two halves ( 50% data on either side ).
  • In order to know the deviation from the mean , standard deviation is used as the unit of measurement.
  • Mean , median and mode of the distribution are equal and located at the peak.
  • In statistics, the area under the normal distribution curve and above the horizontal axis is the total of the all the probabilities of all observations. Thus, the area under the normal curve is 1.

NOTE: Please note that the explanation herein will be brief , for more information books will be added in the reference section.



McLeod, S. A. (2019, May 28). Introduction to the normal distribution (bell curve). Simply psychology: https://www.simplypsychology.org/normal-distribution.html