I think the use of percentages in the 100s is meaningless. Percentages are only really useful when the changes are small w.r.t. the mean. People even have trouble understanding how to compute a pre-tax price when tax may only be 20% added to the base sales price ... and that relationship is clearly defined too.

Some newspapers are being careful at the moment to retain the shock value of percentages in their hundreds, while trying to be rigorous. An increase of 867% is often seen in a headline and if you look carefully at the numbers used, you'll (usually) see that the new value is 9.67x the old value.

I work in software and on a product that's intended to be judged on its (speed) performance. Speed gains need to be given using clearly defined terms. E.g. total execution time reduced by x%. An x% performance "improvement" is ambiguous (some might even say it's deliberate). If the product runs x% faster, it doesn't have its run time reduced by x%.

- Steve

More...

"2 or 3 times faster" is still murky. Try telling the marketing team that your product is 1 times faster (runs twice the original speed, completes in half the original time) and wait for the blank look.

- Steve

10k to 100k ...

a) increased 900% (increase is 9 times the original value)
b) have increased 1000% (now 10 times the original value)
c) 800% (your number) ??

the problem with %ages is you have to know the base value.

Quando Omni Flunkus Moritati

If the base is <old number>:

A 5 percent increase yields <old number> x 1.05
A 100 percent increase yields <old number> x 2
A 900 percent increase yields <old number> x 10

Now, put those numbers in the hands of a marketer, and you'll get unfathomable results.

Speaking of which, how can a detergent get clothes 64 percent whiter?

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

Re: 64% whiter

It is a sunlight/ultraviolet light trick. It looks whiter because the detergent has an optical brightening agent which absorbs light and re-emits it so the whites look whiter under florescent light or sunlight. That's what my physics teacher told us when we were covering light and related topics.

By starting out 64% more dirty.

100% faster = 200% as fast (twice as fast.)

a warning for those whose first language is not English:

"1000% faster" and "1000% as fast" are not the same thing.

A.

Advertisers don't have English as a first language. Whatever sounds the best makes copy, so long as it's not an actual lie.

I like the phrase "New xyz mouthwash removes up to 56% more plaque than brushing alone". One company is using it a lot on TV at the moment. It means that their product can't exceed 56% and can't add plaque. Anything else goes. Like "has zero effect other than smelling of booze".

- Steve

truth in advertising ?

Quando Omni Flunkus Moritati

I can buy an item for 60% percent of the retail price. Somebody else can buy the same item (different state, perhaps) at 50 percent of retail price.

Is that a 10 percent difference?

f-d

¡papá gordo ain’t no madre flaca!

Nope.

Unless you bought it online with free shipping, and other-state-person bought it brick and mortar and paid 8% in taxes.
For a $100 item, you paid $60 and other-state-person paid $50x1.08 = $54.
$60-$54 = $6
$6/$60 = 10%

But since I can't find a US state with exactly 8% sales tax, and don't feel like looking internationally, I guess the answer is still no.

The one that always bugs me is a quoted x% improvement in fuel economy. Is that x% further for the same amount of fuel or x% less fuel for a given distance? It's never stated and probably never even questioned.

- Steve

So when they say that Thing A is "twice as samll as" Thing B, is Thing A even there?

Who knows?

Mike

With taxes, it always depends on whether it is gross or nett. eg in UK, we pay 20% VAT on the (net - expenses). As a computer contactor you can opt to pay 13% of gross so it is just the case of working out whether

VAT = (nett - expenses) * .20

is more than

VAT = 0.13 * (nett * 1.20)

Many contractors have been caught out by paying (nett * 0.13) and then having to recalculate and pay the difference + interest. Of course, the tax office, being very efficient at earning money, will wait about 5 years before they tell you that you've made an error so you have to pay 5 year's interest in back taxes.

About fifteen to twenty years ago, I had a couple of vendors tell me their computer stuff was "an order of magnitude faster". This is a bad thing to say to techies, since we actually know what that means. I have not heard it lately.

On a computer, an order of magnitude could, of course, be two.

--
JHG

Quote:

...On a computer, an order of magnitude could, of course, be two....

Still, a bit faster than before

STF

ok, how about "exponentially" faster, better, etc.

0.5 can be an exponent. So can zero. Can exponents be negative?

I really don't want my new computer to be 10^-10 as fast...

Jay Maechtlen
http://www.laserpubs.com/techcomm

Just faster, it is ok. How much faster? From the start up of the run, up to the velocity of light, there is an infinity of "fasters"

I managed to persuade our commercial people to be precise yesterday. "An x% reduction in execution time." will be in our next set of release notes.

- Steve

Quote:

Dr. Thomas Povey, an Oxford professor who spends most of his time building jet engines, invented a pan that boils liquids faster and saves 40 percent more energy than ordinary cookware.

I'm not sure how ordinary cookware can save any energy.

http://techpageone.dell.com/downtime/flare-pans-a-...

From the article:

"Povey came up with the idea for Flare pans while on a camping trip, where the high altitudes made boiling a pot of water take longer than usual."

I always thought high altitude makes water boil faster: http://www.hi-tm.com/Documents/Calib-boil.html

The water boils at a lower temperature but the little alcohol camp stoves put out much less heat and the ambient temperature tends to be lower so it does take longer to boil a cup of water at high altitude.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

dgallup: The ambient temperature being lower coupled with low BTU stove makes time to boil longer. The altitude still makes time to boil shorter.

% is a little tricky based on how people use it. If our production yield increases by 1% does that mean our 95% yield becomes 96%? That would be common usage where I work. I have had a hard time accepting it and always tend to start into calculations. On the other hand, doesn't it seem kind of strange to use percent of percent? Is that sort of like calling a water heater a hot water heater? (implying that it is used to heat hot water when it is actually used to heat up the cold water)

Hear this!

Our journalists (yes, journalists!) try to make a difference between percent (procent) change and percent units (procentenheter) change. If a political party used to have 40 percent of the votes and they now got 44 percent, that is a 10 percent increase - and a four percent unit increase.

Not all journalists understand it, but they seem to be trying to get it right. That is a good thing.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

I heard an advert recently claiming that XYZ improved success rates of something (stopping smoking, I think) by over 150%. Some serious mathematics there to allow the marketing guys to present the number they wanted. I wonder what it really means. Best I could come up with is that if success is already x, then success using product XYZ will be > 2.5x. I suppose it's assumed that x < 0.4.

- Steve

SomptingGuy, that is a perfect example of lazy thinking. For example, a 20% success rate is obviously double that of a 10% success rate, and is useful information. But to say only that the success rate doubled, without further information, is completely useless and meaningless.
I cringe when I read technical papers, written by engineers or PhD's, where percent change is reported on a temperature. For example, material A has a glass transition temperature of 200C and for material B it is 220C. The author then concludes that the Tg increased 10%. What if the two temperatures were 0C and 20C? Only on an absolute temperature scale is a percent change even possibly correct. Even then, the usefulness of using percent as a comparison is dubious.

fattdad,

My math says that your friend got his shirt for a 10% better discount, you paid 20% more than he did and he paid 16.6% less. If it were me, my wife would say that she can now go buy a purse with the money that I saved. The strange thing is that when it's the other way around and she tells me how much she saved on buying [belt, shoe, scarf, hat], I have asked her to give me the money that *she* saved, but I only seem to get a giggle in return.

My dad had his shoulder operated on a few weeks ago and has sat at home watching (daytime) television while recuperating. Being the sort of person who isn't willing to pay for cable or Netflix, he is watching network television. As a result, I get a twice-weekly debriefing about the current state of affairs and how the world is coming apart at the seams, a notion which may not be without merit.

He explained that Dr. Phil (yes -- he's been reduced to watching Dr. Phil) had a guest who was an alcoholic. When she couldn't find beer, wine or liquor, she started drinking 40% isopropyl alcohol, but when she couldn't find that, she would 70% isopropyl alcohol.

Dr. Phil's response to this was that this is a very bad thing because every time she drinks the 70% isopropyl, she would now be drinking 30% more alcohol than the 40% isopropyl. Needless to say, nobody on the show interrupted him to make the correction.

So stay away from daytime television. And don't tell your wife that you saved money when you buy a shirt.

Engineering is not the science behind building. It is the science behind not building.

That's like the boy who goes to his father and says, "You should be proud of me Dad, I ran home behind the bus tonight and saved a dollar." To which is father replied, "That was stupid. You should have run home behind a cab and saved ten."

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Digital Factory
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.