Statistics for Maintenance Modelling: Basic Probability Concepts

# Variance for Continuous Random Variables¤

The concept of variance can be visualised by looking at the Normal distribution with two different variances. The chart below shows the probability density functions for the Normal distribution with variances 2 = 0.5 and 4.

One can see how the distribution about the expected value (zero) is much different for differing variances. The larger the variance, the wider the spread about the mean.