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Science

How Well Do You Estimate? 374

A random UK blogger has published a quiz asking readers to estimate various numeric values which they may or may not have knowledge of; and has analyzed the resulting answers to determine how well people guess. The first part of the results looks at some specific questions, and the second part takes a look at the quiz overall.
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How Well Do You Estimate?

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  • Estimate (Score:5, Insightful)

    by pklong ( 323451 ) on Friday September 10, 2004 @11:18AM (#10212914) Journal
    I estimate that at about this point all the jokes about estimating will get tedious
  • by dpilot ( 134227 ) on Friday September 10, 2004 @11:26AM (#10213017) Homepage Journal
    I've never actually read MMM, but...

    What really torques me is when you make an estimate early in the program,
    and you know it's only an estimate,
    and since you have only limited information it's not even a very good estimate,
    and you give management all of those caveats up front,
    it just doesn't matter.

    For the rest of the life of the program, better estimates using more information, and even the reality of program execution will all be force-fit back into that original SWAG.

    But sometimes even that original SWAG didn't matter, because it might well have been force-fit into some manager's wish-list.
  • Re:Mirrors (Score:2, Insightful)

    by crazy blade ( 519548 ) on Friday September 10, 2004 @11:30AM (#10213051)

    Perhaps /. scripts should be modified to automatically prepend a Coral [nyu.edu] link to user provided links.

    This way, assuming someone posts a story with:

    at link
    X you will find freebeer!

    It would come up as:

    at link
    X (non-Coral link) you will find freebeer!
  • by MajorDick ( 735308 ) on Friday September 10, 2004 @11:43AM (#10213203)
    My father, a long time IT guy since '63 or so, told me when estimating a project development time take your original SNAP off the top of your head guess , double it , then double it again.

    While I wont say its perfect it comes darn close when you take into account all the administrative overhead, meeting, decisions, etc.

    And since MOST of us developers have a good idead of what our real capablities are. We want to blurt out an ego answer to ourselves, yeah 50 hrs, and if we were in a cage locked up with NOTHING else to do we probably could do it in that timeframe, but bathroom caffine breaks etc take their toll, errr troll
  • by MarkPNeyer ( 729607 ) on Friday September 10, 2004 @11:46AM (#10213237)

    People at large seem to lack important estimation skills. In my observation, people seem to consider a billion, million, and trillion more or less the same. In a December 2003 issue of Vanity Fair, Graydon Carter estimated the U.S. Budget deficit at 6.4 quadrillion dollars. To anyone with an actual understanding of such a number, that figure is completely ludicrous - but it went unoticed by the editors.

    We need increased numerical literacy - so that people understand just how much money 1 million vs. 10 million vs 100 million etc etc actually is. I'm sick of hearing someone say 'are you aware that we spend $x billion dollars a year on thing y?' and then expect me to be outraged or surprised. They just think that 'billion' sounds like a lot - but would they have the same response if it were $x*100 million, or $x*10 billion?

  • by garcia ( 6573 ) * on Friday September 10, 2004 @11:52AM (#10213309)
    Take for example graduating from college. Did you know that there are no "below average" college graduates? Proof: In order to graduate from college you must have a GPA equating to a C or better. A C is average, therefore there are no below average college graduates.

    The average college graduate would be a 3.0 student?
  • by Anonymous Coward on Friday September 10, 2004 @11:55AM (#10213339)
    Take for example graduating from college. Did you know that there are no "below average" college graduates? Proof: In order to graduate from college you must have a GPA equating to a C or better. A C is average, therefore there are no below average college graduates.


    That's not true. Lets say set A is the set of all people going to college. The people who are above the average of set A get to be part of set B, which is the subset of A that graduates. Everyone in set B is above average compared to set A, can be below average relative to the average of set B. So there is definately such a thing as a below average college graduate.
  • by Godeke ( 32895 ) * on Friday September 10, 2004 @11:58AM (#10213357)
    You must not have gone to college then. :)

    Yes, you need at least specific average to *graduate*, but then you don't have any assurance of doing so. My wife teaches at a college and I can assure you that there are many D's and F's given out. However, unlike highschool and social promotion thereof, those people either shape up (and retake the class) or ship out (dropping out). Many do the latter (thus "x years college" being an popular answer to last grade completed).

    Graduate school is a bit different, since you need a B (3.0) average to remain in it. C's are suspension and lower is removal from the program.

    I think the grades represent how some hypothetical "average" community would fair. If you are in college, you *should* fair better than the community, and if you are in graduate school you *should* fair far better than the community. Those who don't shouldn't be at that level.
  • by ack154 ( 591432 ) * on Friday September 10, 2004 @11:59AM (#10213369)
    I'm not sure what school you went to, but 3.0 was a B at Penn State.

    A: 4.0
    A-: 3.67
    B+: 3.33
    B: 3.0
    B-: 2.67
    C+: 2.33
    C: 2.0
    etc.
  • Re:I estimate (Score:4, Insightful)

    by JWW ( 79176 ) on Friday September 10, 2004 @12:23PM (#10213583)
    I think you had it in your first statement. The chances of getting a +5 greatly decrease with relation to the age of the discussion.

    +3 and +4s can be had, but they generally tend to be later posts to a discussion.

    Moderation is not a runaway process than it is a positive feedback loop in relation to time and mod points.
  • Intuitive (Score:2, Insightful)

    by Otto ( 17870 ) on Friday September 10, 2004 @12:30PM (#10213677) Homepage Journal
    Yes, that is a good method, but it's only good in a limited number of cases. What 72 + 137? You don't get the correct answer of 209 quite so easily, unless you estimate to 10's and 5's, or 10's and 25's. Not nearly as simple.

    The method I used, but wasn't exactly taught in school, was to consider it as a quantity and move items from one to the other. In your case, I would have most likely moved 2 from 97 into the 198. Thus making a pile of 95 and a pile of 200, which is easy to add, obviously. This works for the 72+137 problem as well, albeit slightly more complicatedly: Move 3 from 137 to 72, giving 75 and 134. Now move 25 giving 100 and 109. The 109 is arrived at in the head because you're taking away 25 from 134, and that's 134 - 24 - 1 (same moving things around process as adding, but with reversed signs).

    It's simpler to do in the head than it is to explain in words, because really you're thinking of piles of objects and moving them around. Think of subtractions as a hole in the ground that can hold so many, and moving that many objects from the pile into the hole. Helped me when I was learning that stuff when growing up, anyway. I believe I was 6 at the time. ;)

  • Statistics (Score:3, Insightful)

    by chihowa ( 366380 ) on Friday September 10, 2004 @12:31PM (#10213685)
    Actually the center of the range would be a 3.0. If the average student in attendance (counting those who wont graduate) scores a 2.0, then the average of the graduating students will be shifted toward 2.0, assuming a normal distribution.

    Just because you make an arbitrary cutoff at 2.0, that doesn't suddenly shift the distribution to be recentered around the center of the new range.

    For example, if you don't allow people with below 100 IQ to enter a room, the average IQ of the room will be higher than the average IQ of the human population. But the average IQ of the room will still be closer to 100 than, say, 125 because there are many more people With an IQ of 100 than people with an IQ of 150.

  • by servognome ( 738846 ) on Friday September 10, 2004 @12:48PM (#10213830)
    Did you know that there are no "below average" college graduates? Proof: In order to graduate from college you must have a GPA equating to a C or better.
    That is because grades should be a reflection of a student's mastery of the material, not how a student relates to their peers. There are classes where 70% is an A, not to get more students with A's but because that is the expected level of understanding. In fact, that class had less A's than most others with the typical 90% scale.
    Ask an American and a Japanese if they are "good in math". The Japanese will typically say "no", the American will say "yes".
    Most Americans feel they are not good at math and ungood at egnlish.
  • Re:Intuitive (Score:2, Insightful)

    by Anonymous Coward on Friday September 10, 2004 @12:53PM (#10213888)
    wouldn't it be better, for 72+137 to take
    70+130+2+7
    200+9
    209

    and be done? it's much better than getting those 25's (after all, -as a math teacher - i find that most kids have trouble with substracions)
  • by MarkLR ( 236125 ) on Friday September 10, 2004 @12:57PM (#10213924)
    Some of the questions in the quiz are not suitable for estimation.

    For example answering "the year that Harold II became King of England" requires knowledge of English history. Any answer prior to the mid 1900s is a reasonable one for a person who only knows about Queen Elizabeth II.

    People with more knowledge know this a pre-Norman Conquest King and so the answer must be before 1066. But that reduction in the scope of the answer comes from existing knowledge not by estimating.
  • by PMuse ( 320639 ) on Friday September 10, 2004 @02:09PM (#10214649)
    A fine quiz, but I hope he throws out his non-UK results by IP before he uses the data. For many of those topics, my poor American brain had no basis for an estimate and knew it.

    The data could be improved by adding the a "no-confidence" checkbox to each question in addition to demanding a numeric answer. With this, he could compare whether people's estimates were better or worse where they thought they knew the answer. This would make a nice complement to measuring raw estimating power.
  • by jabuzz ( 182671 ) on Friday September 10, 2004 @02:19PM (#10214785) Homepage
    Last time I checked Egypt, Libya, Algeria, Tunisia, Morocco where all on the continent of Africa. These countries are largely populated by people of Arab extraction who I would never describe in a million years as black, and are certainly not Nego. However if any of these people emigrate to America they are technically African-Americans who are not black, no matter how the census bureau tries to define the term. Just because the majority of people of African descent in America in black does not make everyone from Africa black.
  • by hackstraw ( 262471 ) * on Friday September 10, 2004 @03:04PM (#10215264)
    You must not have gone to college then. :)

    Actually, I did and have either been in college or employed by one for 15 of the past 17 years, and that silly argument was a rip off of a position by a professor of mine when I was a senior in college. He was trying to emphasize how grades have been inflated over they years in American universities. He stated that by the university's definition that "C" was "average". Also, by the university's rules one must have a "C" or better to graduate (this was a fairly new rule, you used to be able to graduate with a "D"). So by that logic, and by that logic alone, there are no "below average" college graduates.

    I thought it was cute, and fun, not something that was to be debated.

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