Occasionally we will post papers or articles that will be of interest to some of the visitors to our site.

SPC Fundamentals

This is a very abbreviated introduction to Statistical Process Control that I presented as a webinar for the Indianapolis ASQ Section in July 2017. It describes in very simple and non-statistical terms what SPC is and does.

Listen to Your Customers (But Don't Believe Everything They Say)

In the Quality profession we are taught that quality is all about meeting or exceeding customer needs. If we want to know what customers need, we can simply ask them, right? Actually, there are a number of situations in which customers are unable or unwilling to articulate what they really need. Learn why this is and how to discover the customers' real needs.

A companion presentation is here.

"Jitter Plots" for Visualizing Discrete Data

Do you ever need to visualize the relationship between two discrete variables like satisfaction ratings on a Likert scale? A simple scatter plot isn't effective because multiple points will plot directly atop each other obscuring concentrations of points. My simple solution is something I call a "jitter plot".

Operating Characteristic Curve Comparator

Would you like to make a side by side comparison of the operating characteristic (OC) curves of two different sampling plans? This tool in Microsoft excel makes it easy to see both curves on the same graph. Instructions are here.

What Does SPC Really Do?

Have you heard of Statistical Process Control but don't really know what it does? Here's a non-technical discussion of what you do with SPC and how it helps you improve products and processes.

Budget Friendly Statistical Software

Are you wondering if you need to spend more than $1000 on a dedicated statistical package? You may be able to do what you need with a low-cost (or no-cost) option.

What You Should Know About AQL Acceptance Sampling: Producer's and Consumer's Risk

AQL (Acceptable Quality Level) Acceptance Sampling is sometimes used to accept or reject product lots. The use of this technique has risks for buyers that may not be fully appreciated.

Market Segmentation Using K-Means Cluster Analysis

Cluster analysis is a technique for dividing a multi-variate data set into clusters. Clusters are groups of observations which are more similar within groups than they are between different groups. K-means is a mathematical technique for doing the grouping. Marketing organizations use cluster analysis to identify groups of customers with similar needs and determine how the needs differ from group to group.

Understanding Stratification in Statistical Process Control
In Statistical Process Control (SPC), the term stratification refers to a family of unusual and misleading patterns that may appear when data from more than one machine or process is charted on a single SPC chart. This white paper shows what stratification patterns look like and explains why they occur.

SPC Formulas and Constants

While not technically a "white paper", this document contains a number of handy formulas and constants useful for constructing Statistical Process Control charts by hand or with spreadsheet software. It includes formulas and required constants for most common control charts for both variables and attribute data.