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…moving into the House of Quality

Heading in the Right Direction

September 30th, 2007 by Peter Wolfe

Have you ever watched a team of engineers modifying their secondary requirements (a.k.a. the “quality characteristics hierarchy” or “hows”) on a House of Quality spreadsheet? They remind me of a group of hillbillies staring at a piece of modern art—their heads are usually cocked to the side with grimaced looks on their faces. (It’s quite entertaining actually.) Considering that in a spreadsheet environment secondary requirements are generally edited far more than primary requirements (the primary requirements list or “demanded quality hierarchy” is usually pulled automatically from other Houses of Quality in the QFD), have you ever wondered why it is that the secondary requirements are the ones that are flipped on their sides and run across the top of the HOQ?

The Amazing Pencil and Paper

I think that the root of the problem lies with paper: Paper is a fantastic tool. It doesn’t ask you if you want to save your changes. It doesn’t restrict what values you are allowed to enter on it. It doesn’t run out of batteries or shut down in a power outage. It also doesn’t restrict you in terms of how you look at it—you can rotate it, flip it, or even fold it with very little effort. Computer applications and spreadsheets are not nearly as accommodating.

Remember that the Quality Function Deployment tool existed decades before mainstream computer usage. In the 70’s and 80’s most QFDs were created with a pencil and paper. Although spreadsheets offer significant computational assistance when filling out a House of Quality, they also introduce certain limitations that paper doesn’t have. One of these limitations is the ability to quickly and easily rotate what you are looking at.

Additionally, paper doesn’t have the ability to automatically pull certain pieces of data from another piece of paper in the same way that a spreadsheet can pull data from another worksheet. Thus, when you are working with a paper-based House of Quality, you are just as likely to have to manually edit your primary requirements list as you are to edit your secondary requirements list.

Because it was paper-based, there was no benefit one way or the other as to which set of requirements took which axis when the QFD tool was originally created. Most people just rotated their page to write in secondary requirements, and there was no reason to swap the orientation of the primary and secondary requirements. Today, however, very few people produce Quality Function Deployment models by hand. Most engineering and management teams use proprietary software or spreadsheets (and you’ll note that rotating most monitors is not nearly as easy as rotating a piece of paper).

Furthermore, most Houses of Quality have significantly more secondary requirements than primary requirements. When using a solution such as Microsoft’s™ Excel to create your QFD, you’ll notice that you are allowed significantly fewer columns than you are rows (1/256 as many to be exact). Although many QFDs will never run out of columns for their secondary requirements, this situation can cause some conflict. There are times when teams want to brainstorm possible requirements or enter every request that they have received into an HOQ and then trim the list down later. In these situations, the orientation of the House of Quality combined with the limitations of the spreadsheet will keep the team from being able to add all of the items that they wish to their HOQ.

Is That Really Allowed?!?

If you have experienced similar frustrations, you might be wondering what you can do about it. Believe it or not (now you had better hold onto your hats…), you can change the orientation of your HOQs. Go ahead and run your secondary requirements down the side and your primary requirements across the top. I know that such an idea may seem like sacrilege in the eyes of many Quality Function Deployment purists, but the fact of the matter is that if it will help you use the tool more successfully, then you should make the change.

I started creating my QFDs with this type of orientation about a year ago, and it has never had any negative repercussions to speak of—The QFD police haven’t arrested me. My data hasn’t fallen out of the side of my HOQs. I haven’t detected any tears in the space-time continuum. The only negative side affect that I have experienced is that I haven’t been able to entertain myself by watching rooms full of engineers sit and stare at a projected House of Quality like the RCA dog staring at its phonograph. On the positive side, however, I have noticed that my QFDs are easier for me and my team to create, modify, and maintain. So if you are looking for a way to simplify your QFD process, you just might find that changing the direction of your headings may get you heading in the right direction.

This entry was posted on Sunday, September 30th, 2007 at 7:00 pm and is filed under House of Quality, Advice, Remodeling the HOQ™, Quality Function Deployment, QFD. You can follow any responses to this entry through the RSS 2.0 feed. You can also leave a response.

2 responses about “Heading in the Right Direction”

  1. Justin said:

    You mentioned that the column restrictions imposed by Excel, etc. may be too limiting for an HOQ. I have been told that no HOQ should ever have more than 30 or 40 requirements in any of its lists in order to keep it maintainable. Therefore, I really don’t think that the column restrictions are much of an issue considering that Excel allows 256 columns.

  2. Peter said:

    Justin - if you haven’t already done so, you should check out Joseph Merts’ article “When to Say When” posted back in June. He makes some pretty interesting comments about limiting requirements to a “magic number” or “rule of thumb”.

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