Measurement System


Need I say more? Yes, I suppose I do. Believe it or not, The US formally made it legal to use the SI system in 1866. So why isn’t being used? Habit and cost; the usual impediments to progress.

Of course if you take into consideration the costs of errors due to conversions and using mixed units (see the Mars lander) , then the cost of moving to the world standard is cheap. Habit is harder to combat. Until you actually start using it.

Working in the shipbuiding industry I am pretty used to working with mixed units, or at least to different designs using different systems. The advantages of the decimal system are clear in all the calculations we normally do. Consider a simple case:

1 foot + 1 1/3 inches = ?

10 cm + 22 mm = ?

Which was easier? And how many of us have had trouble at home with measuring with tape measures; calculating centers, adding measurements, converting, etc. I know I’ve screwed up more than one project because of this. On the other hand, my airplane project is almost entirely metric, in mm, and even though it isn’t the system I grew up with, it is so much easier that I can’t really imagine going back to English measurements. Only bolts (SAE sizes) and aluminum sheet thicknesses are in English and these are necessary since these are only widely available in the US in the English system.

Cost aside, it would only take one generation for the SI system to take hold. We are in a global society now, we need to get on board and stop thinking that we are special cases.

What do you think?

BTW, according to Wikipedia, only the US, Liberia, and Myanmar don’t have the SI system as their official measurement system.  Aren’t we in good company.

Published in: on April 22, 2009 at 5:18 pm  Leave a Comment  

Design by PowerPoint

Might as well dive right into the deep end and talk about one of my “favorite” manifestations of Bad Engineering.  

How many of you cringe when you hear the words, “make up some slides on this”, or “need to make a brief …” or “next slide please.”?  Well, you should.  

Okay, okay, I’ll concede that there is a purpose for Powerpoint-like tools in some circumstances, but what I cringe about is the use of powerpoint presentations as a substitute to technical reports.  It used to be that you might make some presentation viewgraphs (foils, transparencies, etc.) after you had written the report.  Now we just skip the report altogether and go right to the powerpoint.  What’s wrong with this?  Well, nothing, if you are purposely trying to keep your audience in the dark.  Course this is mainly due to how the briefs are constructed.

You know the drill, you’ve been in countless meeting where someone stands at the lectern, looks at the screen, and reads slide after countless slides until the audience is asleep or have blown their brains out.  Let me tell you, this is not the way to get your message out, and it is certainly not the way to do engineering.  Even if you aren’t verbose in the slides, the very format of the powerpoint presentation counters richness of detail that is so important in engineering.

This hasn’t been lost on some people who haven’t been seduced by the cheap allure of a gizmo-ridden slide.  Powerpoint was identified as a major source of the widespread technical communication problem at NASA by the Columbia Accident Investigation Board (CAIB):

As information gets passed up an organizational hierarchy, from people who do analysis to mid-level managers to high-level leadership, key explanations and supporting information is filtered out.  In this context, it is easy to understand how a senior manager might read this PowerPoint slide and not realize that it addresses a life-threatening situation.

At many points during the investigation, the Board was surprised to receive similar presentation slides from NASA officials in place of technical reports.  The Board views the endimic use of PowerPoint briefing slides instead of technical papers as an illustration of the problematic methods of technical communication at NASA.

[Columbia Accident Investigation Board, Report, volume 1 (August 2003), p. 191.]

The problems with PP and its ilk are masterfully discussed in the great Edward Tufte’s pamphlet, The Cognitive Style of PowerPoint.  He discussed not only the problems with bullet points and incomplete sentences, but the inability for PP to handle high information density.  I urge you to get a copy (or a few to spread around).



What is the alternative, I hear you ask.  Well, here’s what I do now.  I write a technical report with all the explanations, data, and information graphics.  This I provide in advance of any briefings.  If a briefing is still needed, and if it is just a few people in an office or small conference room, then I pull out the important points, data, and graphics and put together an 11X17 briefing sheet that usually provides plenty of room to contain all the detail I want.  Besides, they always have my original report to refer to later, if needed.  I use this handout as my brief and go through it as a lap brief.  If the brief is to a larger audience, I use the same handout but project the major data graphics on the screen – sans gizmos, flying text, or 3D cartoon graphs.  

Yeah, I know.  It’s tough to buck against decades of mediocre briefings and even harder to sit down and write the report when you know that a quick PP presentation would do.  But then that would be Bad Engineering.  And we don’t do that here, right?

(Oh and by the way, if you do use powerpoint, for cripe’s sake make it a pps file so you aren’t fumbling around for the “play presentation” button.)

Published in: on April 18, 2009 at 10:07 pm  Leave a Comment