In this video tutorial I show how you can estimate the d2 constant and d3 constant. Employing Minitab, we will generate k = 1 million subgroups where each subgroup has n=2 values. Using this simulated data, we will estimate the control chart constants; d2 and d3. For this case, the real value of the d2 […]

# Statistical Engineering

## When to use an Xbar R Chart versus Xbar S Chart ? It depends on the Subgroup Sample Size

Xbar R Chart versus Xbar S Chart I recently got a question from a reader that wanted to know when to use an Xbar R chart versus Xbar S chart. In this post, I will answer that question. Well, the decision to use either of these Statistical Process Control Charts comes down to how the […]

## Xbar and R Chart Formula and Constants | The Definitive Guide Deriving Control Chart Constants: d2, d3, A2, D3, D4 and Computing Control Limits

Have you ever had to prepare an Average and Range Chart? If so, you most likely used some type of software package to display your data and compute the necessary control limits for your Xbar and R chart. But, have you ever wondered how these control limits for an Xbar and R chart were computed? […]

## Quality by Experimental Design – 4th Edition Book Publication Announcement | February 17, 2016

Quality by Experimental Design – 4th Edition | Book Publication Announcement Quality by Experiment Design is due for release February 17, 2016. Are you interested in designing experiments that try to solve technical problems tied to strategic business, productivity or innovation initiatives? If so, then Quality by Experimental Design is a great companion text that will […]

## Control Chart Constants – How to Derive A2 and E2 Learn how to derive the E2 and A2 control chart constants used to compute control limits for the X-bar and Individuals Charts

Control Chart Constants, where did the A2 and E2 constants come from? In statistical process control (SPC) charting, we use the A2 and E2 constants to calculate control limits for an Average (X-bar chart) and Individuals charts. But where do the A2 and E2 constants come from? Let’s look at the following example, for an X-bar […]