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More Numbers

More Numbers

More Numbers

(OP)
Check out this week’s Time  (1 Mar 2004 issue date)

On page 42 of the Canadian edition there is a box on trends in cosmetic surgery. It’s in a US story  so it should also be in the US edition but might be on a different page.

It shows two pie charts. These pie charts give the breakdowns in where the procedures were performed office, hospital or freestanding clinic for the years 2003 and 1997. The freestanding percentage was 23% both years but the office percentage increased from 46% to 52%.

The text says that the percentage change in procedures performed in an office was 13 % increase. This is only correct if one is referring to the percent change in the percent of procedures performed in an office, which is a meaningless number due to the increase in total procedures.

In 1997 the total number of procedures was 2.1 million, 46% of this translates into 970,000 office procedures. In 2003 the total number of procedures was 8.3 million, 52% of that translates into 4.32 million office procedures.

The correct percentage in office procedures was therefore ((4.32/0.97)-1)x100= 347% increase.

Even the major national and international publications get it wrong.

Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion
www.kitsonengineering.com

RE: More Numbers

Sounds like they should have said
"The change in procedures performed in an office as fraction of total 1997 surgeries was 13%".

If they provide the data, I personally give 'em some latitude to be brief in their summary.

If they don't provide the data, you never really know whether they're telling it right or not.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

RE: More Numbers

Things like this are the reason folks from human resources, media, etc. can't stand engineers... we always find the flaws in their data!

I'm obviously not alone in my distaste for mis-used statistics.

RE: More Numbers

In this case it's not, as the article states, "... percentage change in procedures performed in an office was 13 % increase...", it is the ratio of in-office to in-hospital procedures that increased 13%.  I'm not quite sure that it's a misuse of a statistic, but rather a misunderstanding of what the statistic represents.  In this case, I'd lean towards giving the benefit of the doubt that the author doesn't understand what is being said.  (hold that thought)

I do agree that the mis-use of statistics is quite distasteful, and can be quite harmful, especially when it's used, not to discuss the data set and it's implications, but rather to incite others to take unwarranted action.  If the previous author mis-stated the 13% increase claim for the purposes of, let's say enacting some medical legislation, then it is a harmful misuse, and not a misunderstanding.  To me it's more a reflection of motive.

As we in the USA approach our Presidential election, we can expect both sides to grossly misuse statistics.

RE: More Numbers

I have a favorite quote on stats....often misattributed to Mark Twain (who actually attributed it to Disraeli)...Benjamin Disraeli & Leonard H. Courtney are also attributed: "There are three kinds of lies: lies, damned lies, and statistics."

There is some argument as to who actually originated this infamous quote. Earlies printing of such appears to be J. A. Baines using the phrase in J. of the Royal Statistical Society 59 (1895) 87. He quotes his friend and fellow statistician, M.P., later Lord, Courtney, in "recent" use.

RE: More Numbers

If you want to inspire confidence, give plenty of statistics. It does not matter that they should be accurate, or even intelligible, as long as there is enough of them.
Author: Lewis Carroll

RE: More Numbers

Is there a problem with numbers in North America?

The film, "The madness of George III" was apparently re-named "The madness of King George" because the "III" would make audiences (I won't say which country they were alluding to) believe it was a second sequel and that they had missed the first two films.

Now I read that the new Aston Martin DB9 has been launched to replace the DB7. Where, asks the article, is the DB8? quietly aborted because it was felt that

Quote:

"customers, Amewricans in particular, would be puzzled by a car that had 12 cylinders and an "8" on the back. SO instead, the new car is called the DB9. No chuck, it does not have 9 cylinders."

Are numbers becoming a more universal problem?
Are numbers often used ambiguously?

Does it happen in engineering?
Well, yes, I think so.
How many of you encounter that confusion between SCFM and ACFM in gas flow? or are mystified by the diference between "standard" and "normal"? (n/N?ormal)
Many times times people quote viscosity without referencing the temperature. This can be a problem with fuels because the standards use 100degC as the reference yet the industry commonly describes fuels by their 50degC temperature.
So people quite often refer to a 380cSt fuel which, by the standards, is a 35cSt fuel. Here the distinction is clear enough as there is an order of magnitude difference, or is it?

So people economical with their words often leave of vital inforation but this shorthand is only inteligable to those in the know; for others, a tad confusing at times.

JMW
www.viscoanalyser.com

RE: More Numbers

The author quoted above does not know how to spell.  Considering his opinion of Americans, that is just one more thing to dislike about him.

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Eng-tips forums: The best place on the web for engineering discussions.

RE: More Numbers

dang it..  

And I was so sure my SR5 had 5 cylinders.

TTFN

RE: More Numbers

(OP)
My Volvo 850 has 5 cylinders.

It says in big letters on the valve cover “20 valves”. After 10 years I am amazed that a lot of people have trouble figuring out that that means a 5-cylinder engine.

Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion
www.kitsonengineering.com

RE: More Numbers

Rick,

Sorry to correct you, but my VW has 20 valves, but it is a five valve per cylinder four cylinder engine.

Cory

RE: More Numbers

And then of course the Viper has a V10 with 2 valves per cylinder.

Cheers

Greg Locock

RE: More Numbers

Amewricans were so confused when Triumph introduced the TR3 in the sixties, thinking the car only had 3 cylinders, that we did not buy many of them. It had nothing to do with the fact that they broke down every week and cost a king's ransom to repair!

Speaking of Monarchs I did see "The madness of King George III" and was not confused in the least about whether it was the second sequel. I did enjoy the historic content and learned that inbreeding is a bad thing. I also knew such a banal subject would not warrant 2 sequels.

It is amazing how such rubes have become the world leader in technology and the only remaining world super power. I guess us renegade colonists are just to dang stupid to realize it was just dumb luck.

The above tirade is all in jest JMW. I'm just funnin' with Ya'll!

RE: More Numbers

TwnB, no problem to me, I'm not irrelevant, I'm a hippopotamus (plural hippopotami, according to Flanders and Swan)i.e thick skinned.

The great advantage of being a multinational with an all-encompassing choice of ancestors is that I can poke fun at all my "nationalities". That is, except that in conversation, especially in pubs, it takes too long, after the joke, to explain that "some of my best friends are Americans/Irish/Scottish/red-necks/etc" beore being thunped; a forum is not as much fun (you have to bring your own drinks) but decidedly safer.

The problem is, as ever, that some people can't discriminate between "affectionate" and "derogatory" though much, like beauty, is in the eye or mind of the beholder and or recipient.
In this PC world (not IBM, the other) a lot of good jokes are going to waste.

JMW
www.viscoanalyser.com

RE: More Numbers

When speaking of numbers and misused statistics I cannot but remember The Reader's Digest dictum:

It is now proved beyond all reasonable doubt that smoking is one of the leading causes of statistics.

And another of anonymous origin:

If you just torture tha data long enough, they will confess.

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