## How is Sigma Estimated from a Control Chart?

Sigma – an important statistic for us to know. Sigma, or the standard deviation, is a measure of how much dispersion there is in a process. There are numerous ways to estimate sigma. One way, of course, is simply to calculate the value using the formula for the standard deviation:

## Where are Control Charts Used? [video]

This is the fourth and last blog in our four-part series introducing control charts. The first blog addressed the question of what a control chart is. The second blog explored the relationship between variation and control charts. The third blog addressed the purpose of a control chart. This blog answers the following question:

Where are control charts used?

## What is the Purpose of a Control Chart?

This is the third in a four-part series introducing control charts. The first blog addressed the question of what a control chart is. The second blog explored the relationship between variation and control charts. This blog begins to answer the following question:

What is the purpose of a control chart?

## Variation and Control Charts

This is the second in a four-part series introducing control charts. The first blog addressed the question of what a control chart is. This blog will answer the following question:

What is variation and how does it relate to a control chart?

## What is a Control Chart?

This is the start of a four-part blog on control charts. The blogs will answer the following questions:

#### SPC Knowledge Base

Sign up for our FREE monthly publication featuring SPC techniques and other statistical topics.