ABSTRACT
Statistics are extremely important in the career of the safety professional. Safety professionals utilize them to report their annual injury and accident rates, calculate failure probability rates, and describe observed or experimental data. Descriptive statistics are used to describe a set of data. The mean is also referred to as the "average" or arithmetic mean. The mean describes the central location of the data, and the standard deviation describes the spread. One method of testing a hypothesis of a correlation between variables is to use the Spearman rank coefficient. In statistics, a standard score indicates how many standard deviations an observation or datum is above or below the mean. Standard scores are also called z-values, z-scores, normal scores, and standardized variables; the use of "Z" is because the normal distribution is also known as the "Z distribution". Reliability is the ability of a system or component to perform its required functions under stated conditions for a specified period.
