An excellent calculation is one that:

1. Meets the customer’s expectations, needs, and requirements.
2. Stands out in both professional appearance and high quality content.
3. Is clear, succinct, and organized to lead the reader from purpose to conclusion in a logical easy to follow manner.
4. Is produced efficiently and meets deadline commitments.

Excellent calculations depend on people who care. An engineer’s attitude and mindset when preparing or reviewing a calculation determine the quality of the end product.

This post delves into specific recommendations to be applied to calculations. Refer to post “4 Tips for Delivering a Quality Engineering Documents” for higher level tips for producing quality engineering deliverables in general.

Ten recommendations for producing excellent calculations:

1. Sign with confidence. Remember, as preparer, reviewer, or approver, your signature is going on this calculation. Before you sign, be confident that the document meets your personal standard of excellence, is correct, complies with governing procedures, and you are qualified to sign.
2. Assume mistakes exist and find them.
3. Develop a “mutual accountability” mindset. By mutual accountability I mean that both the preparer and reviewer are equally accountable for quality. If you are the preparer, don’t rely on the reviewer to catch your mistakes. If you are the reviewer, own the calculation like it is your own, because it is.
4. Anticipate problems. During initial planning, think ahead about the likely obstacles and budget sufficient time to deal with problems without impacting deadlines. Too often we use obstacles along the way as excuses to miss a deadline. Use the planning you have done to push back with facts if unrealistic deadlines are imposed.
5. Ensure traceability by referencing sources for your inputs. Ensure inputs are traceable with specific references so a knowledgeable engineer can find and confirm the appropriateness of inputs without recourse to the preparer. For example, if citing an equation in a text book, don’t just cite the book title, author, and date; cite the chapter, section, and page if necessary to ensure traceability.
6. Use assumptions sparingly and provide justification that their use is appropriate for the application. If an assumption needs confirmation by a later step in the design process, the calculation should note this and a tracking mechanism is needed to limit the calculation’s use until the confirmation is completed.
7. Number pages to ensure a hard copy version of the calculation can pass the “drop test”.  Say you have a 200+ page document and it is dropped on the floor.  Passing the drop test means someone can gather all the pages off the floor and put the document back together again with all pages in the correct order!
8. Follow the governing procedures.  Sounds simple, but for some reason, alot of calculations don’t fully comply with procedures.  Remember, procedures, if developed properly, are continuously evolving and improving based on the lessons learned from past mistakes.  Following and proactively improving procedures are important barriers to repeating past mistakes and essential in the quest for excellence.
9. Scrutinize the appropriateness of all inputs. I find that most technical errors in calculations are because of the use of incorrect inputs.  This is critical to understand because many errors in calculations are “latent errors”.  A latent error is not self revealing, and it may be years before it is found, if found at all.
10. Pay attention to details. The price for allowing calculations to be issued with “attention to detail” errors is enormous. Client satisfaction plummets if you cannot deliver calculations free of careless errors.  Often not only must the errors be fixed and the calculation reissued, but cause investigations, group stand-downs, re-training, and procedure changes are imposed to reinforce paying “attention to detail”.  These are all avoidable costs of NOT paying attention to details to begin with.
    Attention to detail errors are any errors that a good final read through should have caught. They include spelling errors, cross referencing errors, grammar errors, legibility issues, procedure non-compliance issues, etc.

I hope these tried and true lessons learned help you in your quest to deliver excellent calculations. I would love to hear about your lessons learned related to calculations and what additional information you would like to have in future blog posts aimed at achieving engineering excellence.