Statistics for Maintenance Modelling: Basic Probability Concepts

# The Normal Distribution¤

An example of the probability density function for the well known Normal (Gaussian) Distribution is given by:

The probability density function for the standard Normal Distribution with = 1 and = 0 is shown here. Click on the chart for an interactive version in Excel where you can experiment with different values of and .

In statistics the Normal distribution is the usual starting point to model a random variable. It is said that the Normal distribution is the distribution of a random variable which is made up of many small
disturbances or effects. Furthermore the Normal distribution is used extensively in statistical inference. With regards to reliability and maintainence the Normal distribution takes on a less important role since lifetime distributions do not allow negative values, whereas the Normal distribution does.