Writing an Operational Definition for a Measure

Our Yellow Belt course includes an assignment where students are required to write an operational definition for measuring something.  An operational definition, when applied to data collection, is a clear, concise and detailed definition of a measure. The need for operational definitions is fundamental when collecting all types of data.

Here is the text of a recent submission by one of my students: “This assignment was a little more difficult because I was trying to find something that I do on a daily basis to use as an example.  I was at the grocery store on a short break when I came across my assignment.  Here is my operational definition for purchasing two pounds of skirt steak:

– Find the skirt steak.

– Find a scale at the supermarket.

– Place the meat on the scale to measure/weigh 2 lbs.

– If the meat weighs/measure over the required 2 lbs., have the butcher remove some meat to get me to my desired amount.

– If the meat weighs/measures less than 2 lbs., have the butcher add more meat to get me to my desired amount.

– Once I get my 2lbs, I have them wrap it up and purchase.

I hope this scenario fits the assignment”.

Here is what I wrote in reply:  “This submission is fine for the purposes of the assignment.  The key learning point with this assignment is to recognize that any instruction that can be misinterpreted will be misinterpreted.  For example, find a scale.  Does it need to be a meat scale?  Is it OK to put meat on a scale that is used for cheese?  Is it OK to put skirt steak on a scale that is used for weighing chicken?  The answer is no in both cases due to potential cross contamination.

How much discrimination does the scale need, in other words how closely must we measure the weight?  Is measuring to the nearest pound OK, or do I need to measure to within .1 pounds or to .01 pounds?  Can I use the scale in the front of the store that people use to weigh themselves?

You stated that the meat should weigh 2 lbs. or else it needs to be trimmed.  What if it weighs 2.01 pounds – is that OK or would we need to trim off .01 pounds?  What if it weighs 2.1 pounds?  How close is close enough?

I trust that you take my point.  We must take every precaution to be very specific about how we want data collected.”

Your comments or questions about this article are welcome, as are suggestions for future articles.  Feel free to contact me by email at roger@keyperformance.com.

About the author:  Mr. Roger C. Ellis is an industrial engineer by training and profession.  He is a Six Sigma Master Black Belt with over 48 years of business experience in a wide range of fields.  Mr. Ellis develops and instructs Six Sigma professional certification courses for Key Performance LLC.   For a more detailed biography, please refer to www.keyperformance.com.