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Author Topic:   What is a Theory?
olivortex
Member (Idle past 3005 days)
Posts: 70
From: versailles, france
Joined: 01-28-2009


Message 241 of 249 (496605)
01-29-2009 9:19 AM
Reply to: Message 240 by prophet
01-28-2009 7:25 PM


Re: Correct terminology (again)
I guess "accuracy" tends to mean precision, exactness, correctness, exactitude. Science is generally running after this. Ambiguity can come from the opposition between two different interpretations of an observation, and also from the potential complexity of the subject being studied.
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Replies to this message:
 Message 242 by Rrhain, posted 01-31-2009 5:56 AM olivortex has responded

    
Rrhain
Member (Idle past 100 days)
Posts: 6349
From: San Diego, CA, USA
Joined: 05-03-2003


Message 242 of 249 (496856)
01-31-2009 5:56 AM
Reply to: Message 241 by olivortex
01-29-2009 9:19 AM


olivortex writes:

quote:
I guess "accuracy" tends to mean precision, exactness, correctness, exactitude.

To be pedantic: Not quite. There is a big difference between "accurate" and "precise."

A "precise" measurement will have a lot of significant digits. An "accurate" measurement will have whatever significant digits it has being correct.

Numbers can be accurate, but not very precise ("3" as the value of pi) and similarly, precise, but not very accurate ("2.71828182845904523536" as the value of pi).

That's one of the ways that you can tell when someone is trying to snow you: Their numbers are extremely precise. They don't have "25%" but rather "24.739%" Really? You were able to measure it that precisely? Your apparatus is capable of providing that level of detail such that you can carry five significant figures?

The goal, of course, is to get both accurate and precise data.

Edited by Rrhain, : Better definition of "accurate"


Rrhain

Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.
This message is a reply to:
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Replies to this message:
 Message 243 by olivortex, posted 01-31-2009 7:00 PM Rrhain has not yet responded
 Message 244 by bluescat48, posted 02-01-2009 12:27 AM Rrhain has responded
 Message 246 by Woodsy, posted 02-01-2009 8:24 AM Rrhain has not yet responded

    
olivortex
Member (Idle past 3005 days)
Posts: 70
From: versailles, france
Joined: 01-28-2009


Message 243 of 249 (496984)
01-31-2009 7:00 PM
Reply to: Message 242 by Rrhain
01-31-2009 5:56 AM


Thanks for your PRECISION :)

I guess my understanding of english will improve thanks to people like you, on this forum. Sometimes it gets way too technical for me, but it can't be useless!

It is true that accurate is not necessarily precise and vice versa. It's a bit like the quality/quantity relationship. By the way i must eat something not too big but good before i go to sleep.

See you!

www.myspace.com/olivortex


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bluescat48
Member (Idle past 2417 days)
Posts: 2347
From: United States
Joined: 10-06-2007


Message 244 of 249 (497007)
02-01-2009 12:27 AM
Reply to: Message 242 by Rrhain
01-31-2009 5:56 AM


Not to be nitpicky but:

("2.71828182845904523536" as the value of pi).

The number you gave is the value of e

which curiously enough rounds to 3 at one place accuracy thus pi = e to zero decimal places.

Edited by bluescat48, : italic


There is no better love between 2 people than mutual respect for each other WT Young, 2002

Who gave anyone the authority to call me an authority on anything. WT Young, 1969


This message is a reply to:
 Message 242 by Rrhain, posted 01-31-2009 5:56 AM Rrhain has responded

Replies to this message:
 Message 245 by cavediver, posted 02-01-2009 6:08 AM bluescat48 has not yet responded
 Message 248 by Rrhain, posted 02-03-2009 2:28 AM bluescat48 has not yet responded

    
cavediver
Member (Idle past 1871 days)
Posts: 4129
From: UK
Joined: 06-16-2005


Message 245 of 249 (497023)
02-01-2009 6:08 AM
Reply to: Message 244 by bluescat48
02-01-2009 12:27 AM


Not to be nitpicky but... The number you gave is the value of e

Yep, that was Rrhain's point - it is a very precise value to give as an answer to the question, "what is Pi?", but it is not at all accurate.


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 Message 244 by bluescat48, posted 02-01-2009 12:27 AM bluescat48 has not yet responded

  
Woodsy
Member (Idle past 1601 days)
Posts: 301
From: Burlington, Canada
Joined: 08-30-2006


Message 246 of 249 (497039)
02-01-2009 8:24 AM
Reply to: Message 242 by Rrhain
01-31-2009 5:56 AM


One of my favourite textbook illustrations was about these ideas. It showed a target with a duck drawn in the middle and various results of shotgun blasts. Closely-spaced groupings were precise, but only those on the centre were accurate. One showed hits all over the place, with none hitting the duck, and was labelled "On average, the duck was dead.".
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 Message 247 by DevilsAdvocate, posted 02-01-2009 8:38 AM Woodsy has not yet responded

  
DevilsAdvocate
Member (Idle past 1328 days)
Posts: 1548
Joined: 06-05-2008


Message 247 of 249 (497044)
02-01-2009 8:38 AM
Reply to: Message 246 by Woodsy
02-01-2009 8:24 AM


Actually similar to Woodsey's duckhunt analogy, in military applications i.e. Naval Gun Fire Support (firing a 5" projectile 3 miles away to take out enemy suppression fire in support of U.S. Marine movement on a beach head), precision and accuracy are very different but related concepts as shown here:


Click to enlarge


Click to enlarge

However, what you want in both military and scientific applications is to be both accurate and precise. That usually gives the best results.

Edited by DevilsAdvocate, : No reason given.


For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.
Dr. Carl Sagan
This message is a reply to:
 Message 246 by Woodsy, posted 02-01-2009 8:24 AM Woodsy has not yet responded

  
Rrhain
Member (Idle past 100 days)
Posts: 6349
From: San Diego, CA, USA
Joined: 05-03-2003


Message 248 of 249 (497250)
02-03-2009 2:28 AM
Reply to: Message 244 by bluescat48
02-01-2009 12:27 AM


bluescat48 responds to me:

quote:
The number you gave is the value of e

How nice to see somebody who knows that. Some people memorized pi. I memorized e. Pi is a button on my calculator, but e is not (I have since acquired a better calculator.) You can get it from using the "ex" function, but not all calculators can do that so it was just easier to memorize the digits.

Indeed, to one significant figure, an "accurate" measurement of both pi and e would be "3." But "3" isn't a very "precise" measurement of either. "3.00000" is extremely precise (because all those zeroes after the decimal point are significant), but it isn't very accurate with regard to pi or e.

eπi + 1 = 0

Because of that, all of reality follows.


Rrhain

Thank you for your submission to Science. Your paper was reviewed by a jury of seventh graders so that they could look for balance and to allow them to make up their own minds. We are sorry to say that they found your paper "bogus," specifically describing the section on the laboratory work "boring." We regret that we will be unable to publish your work at this time.
This message is a reply to:
 Message 244 by bluescat48, posted 02-01-2009 12:27 AM bluescat48 has not yet responded

    
Adminnemooseus
Director
Posts: 3892
Joined: 09-26-2002


Message 249 of 249 (497252)
02-03-2009 4:36 AM


Contact with the topic theme seems to be getting lost
Message contents should have some explicit connection to the question "What is a Theory?".

Adminnemooseus


    
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