Cause and effect problem solving starts with an accurate description of the problem. And the people who experience the problem often know most about how to describe the problem. Recently, I have worked with a client to help them solve a problem that has plagued them for months. One of their manufacturing operations is spending […]

# Statistical Engineering

## Constant Sum Paired Comparison – Assigning a Quantitative Value to a Visual Attribute

Constant Sum Paired Comparison Procedure In the Constant Sum Paired Comparison procedure, a study administrator will gather two objects to form a pair. This pair of objects gets presented, at the same time, to an observer. The observer must decide if there is a difference between the two objects. He or she does so by […]

## Attribute Data vs Variable Data – Which Do You Prefer?

Attribute data vs variable data. If you had a choice, I’m sure you’d pick variable data! I often find Six Sigma practitioners shy away from projects that try to reduce non-conformances. They’d rather work on projects that have a well-defined output variable instead of an attribute. I don’t blame them; I’d rather have a precise […]

## Process Capability, Do You Really Want to Improve It?

Process Capability – What is It? Process capability indices can be misleading. For instance, let’s consider the Cp Index. This process capability index compares the process spread to the tolerance spread. It provides a measure of how well the process can meet a tolerance expectation under certain conditions. Let’s review this in greater detail. Process […]

## Range Statistics and d2 Constant – How to Calculate Standard Deviation

Range Statistics and the d2 Constant Used in Statistical Process Control Charts Range statistics are often used in statistical process control charting. One type of statistical process control chart is the average and range chart. Another type is the individual and moving range chart. To calculate control limits for each SPC chart requires we […]