Normal Distribution

Normal distribution can be tested for by:

a) plotting the data on a graph and visually inspecting the line

b) using a probability graph in which if it is possible to draw a straight line through the values distribution is normal

c) applying the Chi-Square Test for normal distribution.

d) checking whether the mean, mode and median coincide (which they do if distribution is normal)

or

e) testing that:

68% of all values will fall between -1/+1 standard deviation and
95% of all values will fall between -2/+2 standard deviations.