The Manufacturing Academy Article Series

I remember the feeling I had as child when I first heard about Rudolf. I was certain that Santa had eight reindeer. Then suddenly one day, I was wrong. Somehow a ninth reindeer had appeared on the scene and forever altered my view of St. Nick’s tiny sleigh. This feeling of cognitive dissonance recurred years later when I first heard about Cpm – the “Rudolf” of capability indices. I knew about Cp and Cpk. I knew about Pp and Ppk. And I thought that was it. But once again, the mental rug was yanked from beneath me when abruptly I realized there was more. [Read more…]

Several years ago, I was trying to fill a quality engineer’s position within my department. One person’s resume caught my attention. Under a section titled “Areas of Expertise”, it read “Quality Engineering Statistics”. “My gosh”, I thought, “We’ve got to call this guy for an interview. [Read more…]

I recently read the results of a AAA survey where Americans were asked to rate their own driving abilities. 73% of those surveyed considered themselves “better-than-average” drivers. Obviously only 50% of the drivers can actually be better than average. So it follows that at least 23% of those surveyed are mis-estimating their own skills.

This over-confidence in one’s abilities seems to find its way into all sorts of areas … including process capability analysis. Everyone who’s been around manufacturing for any length of time has certainly heard of Cp and Cpk. Most of them know that “higher is better” when it comes to these indices. And many will nod their heads and smile when you suggest that Cpk and Ppk account for centeredness, whereas Cp and Pp do not. But only a small percentage of manufacturing professionals can cogently answer the question, “What is Process Capability analysis?” [Read more…]