## One Sigma Event

A one sigma event is an event that is expected to occur with a probability of about 68%. In a normal distribution, one standard deviation from the mean (average) covers about 68% of the data points. This means that if you have a normal distribution of data and you plot it on a graph, about 68% of the data points will fall within one standard deviation of the mean.

In the context of risk analysis or statistical quality control, a one sigma event might refer to an occurrence that is within the normal range of expectations. For example, if a manufacturing process is producing parts with a certain level of variability, a one sigma event might be a part that falls within the expected range of that variability.

It’s important to note that the term “one sigma event” is used somewhat informally, and the specific definition may vary depending on the context in which it is used.