The ‘Argument of Twelves’ and the Metric System

The fact that we have 12 inches in a foot isn’t a good reason to reject the metric system. Image from arielrobin on Pixabay.

(Sorry for the long lag between posts. I had some things going on in my life that required my full attention. Things are pretty much back on track. Thanks for your patience.)

Awhile back I was fulfilling my role as a scientist ambassador at the Bradbury Science Museum here in Los Alamos, NM. (This mostly consists of setting up various measurement activities and chatting with visitors about the advantages of the metric system for a couple of hours on the occasional Saturday.)

One day I realized that a man was starting to pace back and forth in front of me. Even though I wasn’t yet done prepping and I sensed this gentleman was about to go on the attack, I went ahead and said, “People are dying in this country because we don’t use the metric system in this country.”

“I don’t believe you,” he replied.

Even the Centers for Disease Control recommends strict use of metric units for liquids. (Pills are measured in grams, or a fraction thereof, already.)

I then handed him the 2016 Top Ten Patient Safety Concerns for Healthcare Organizations report put out by ECRI [Emergency Care Research Institute]. Number seven on the list: “Medication Errors Related to Pounds and Kilograms.” It advocates for only using metric system units (i.e. kilograms for weight) to reduce dosing errors since most medications use weight to determine the correct dose. It’s reason is simple: There are about two pounds in a kilogram. Doctors and nurses are schooled in the metric system but have to bounce back and forth between metric and U.S. customary units to communicate with their American patients. If they mix up the two, they might give the patients half the dose they need (potentially rendering it ineffective) or twice the amount (read overdose).

Using metric system units for medicine has also been recommended by multiple health organizations including the Centers for Disease Control. (See the above image)

The gentleman reviewed the report and since—I assume—he could no longer argue on that particular point, he launched into what I’ve now dubbed “The argument of twelves.”

The Argument of Twelves

The argument goes something like this: If you are working with a group/set of 12s, then your factors are 1, 2, 3, 4, 6, and 12; but if you are working in the metric system, your factors are only 1, 2, 5, and 10.

I consider this to be a specious argument since (and please, but nicely correct me if I’m wrong) we don’t really measure a lot of things by twelves. Sure, a foot has twelve inches and there are twelve months in a year. (Apparently eggs are sold by the dozen—according to the New York Times—because eggs were a penny each and there are 12 pennies in a shilling. Selling eggs by the dozen meant, as a vendor, you didn’t have to make change.) However, there isn’t much else I can think of that comes in twelves except a gross of 144 items (which is 12 multiplied by 12). You can’t really cite time because military/Zulu time uses a 24-hour clock.

If we actually had 12 ounces in a cup and 12 cups to a gallon and 12 ounces in a pound and 12 yards to a mile, then I would understand that counter argument. (In reality, there are 8 ounces in a cup, 16 cups and 128 ounces in gallon, 16 ounces in a pound, and 1,760 yards in a mile…plus 36 inches or 3 feet in a yard and so on.)

But, when it comes to everyday measurement, we really only divide up inches, months, and eggs into twelves. I don’t think that’s enough reason to reject using the metric system.

However, I’ve found after seven years on this project (the anniversary of which was the day before yesterday), if people are threatened by the idea of changing to the metric system—for any number of reasons—they will latch onto whatever immediately comes to mind to reject it.

Around the time that the man was winding down his argument of twelves, some other—more open-minded people—approached me and I turned my attention to them.

I’ve said many times that, when it comes to this issue, there are probably 10-20 percent of people who already love the metric system and there’s about another 10-20 percent who are completely opposed to it.

It’s my plan to focus my attention on the 60 to 80 percent who don’t realize we have a problem in this country and are open to learning about it. Maybe action will eventually occur. That’s my hope. If you want to become more involved, let me know at milebehind@gmail.com.

In a closing note: I realize that some people ascribe a historical and religious meaning to the number 12, but we don’t have to limit the number of members on a jury or the number of apostles due to the metric system so let’s not shoehorn that number into our measurement system unnecessarily.

Plan for another post in September.

Thanks for getting this far,

Linda

Conversion errors and the metric system

A recent headline on a metric system conversion error

I recently received news that the Centers for Disease Control and Prevention (CDC) made a major conversion error relating to the metric system. The upshot is that it greatly underestimated the risk of formaldehyde in laminate flooring. The underlying mistake: it failed to convert between meters and feet initially reporting the estimated risk at one-third of what it should have been.

The organization did not come out and say lack of metric adoption was the cause of the error:

The CDC/ATSDR indoor air model used an incorrect value for ceiling height.  As a result, the health risks were calculated using airborne concentration estimates about 3 times lower than they should have been.

However, others were more than happy to point out the real root of the problem:

CDC fixes major error in flooring risk report: Not converting to metric – Retraction watch

CDC Revises Health Risk Assessment Of Flooring After Math Error: CDC recently announced that laminate floors are safe, only to realize that they forgot to convert from feet to meters—and that the cancer risk is three-fold higher – Vocative.com

There are some who believe that conversions are easy to make and therefore, living with two measurement systems shouldn’t be a problem.

Marciano’s book

In fact, in his book, Whatever happened to the metric system: How America kept its feet, John Bemelmans Marciano (Kindle location 2020 for both quotes), states:

Conversion is now as easy as speaking “seven ounces to grams” into your smartphone and immediately receiving the answer 198.446662g.

Marciano later goes on to say:

Why would Americans go metric when computers have done the job for them and they don’t even have to know about it?

How about a three times greater risk for potential negative health effects due to human unit-confusion error?

Luckily, the CDC was able to quickly make a correction but who knows how many other errors haven’t been caught and continue to put us at risk in one way or another?

The idea that technology will save us from conversion errors is flawed because it assumes that the human element won’t impose the error.

Surely the CDC has access to computers and other high-tech gadgets at least as good, if not better, than what I have access to in my smartphone and yet, the mistake was still made.

Again, it’s not a technology issue, it’s a human issue that will always occur even if the frequency of such mistakes is not currently well known.

Aside from outright errors, there’s the time it takes to make a conversion in the first place. Add up the time it takes to whip out the cell phone, ask the question, wait for the answer and read it. Then one needs to multiply that by how many people in this country need to do that in a year. All wasted time. One set of measures eliminates the entire issue.

I’ve previously pointed out people are already at risk every time their pharmacist converts a prescription written in milliliters (as they all are) into teaspoons and tablespoons. Why are we doing this to ourselves?

Conversion errors are inevitable  

While I so far have been unable to find any statistics on how often conversion errors occur, everyone seems to recognize they do happen and research seeks interfaces that try to minimize them. One paper I reviewed, Reducing number entry errors: solving a widespread, serious problem by Thimbleby and Cairns indicates:

Ironically, the more skilled a user, the less attention they will pay to what ought to be routine outcomes, so the more likely these types of error will go unnoticed until they have untoward consequences. The reason is, as users become skilled, they automate actions, so their attention can be used more selectively; thus as they become more skilled, they pay less attention to the display, whose routine behaviour they have learnt to expect (Wickens & Hollands 2000).

A conversion “helper” from the 1970s

Still, we can learn from our past. One of the things I’ve heard from people regarding our last attempt at metric adoption in the 1970s (I was a bit young at the time to remember) was students were taught difficult and confusing conversion formulas.

Next time, just have people start using the new, metric system measures and convert only those things that are absolutely necessary. Fewer conversions means fewer errors.

Thanks for reading.

More next month.

Linda