Slashdot Mirror
How Well Do You Estimate?
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.
I estimate that I would end up somewhere in the middle.
With 44.7% accuracy!
more or less.
I am one of many. My idea is not unique, nor do I expect my voice alone to sway you. I speak in a chorus of opinion.
I would estimate that that server stayed up less than 2 minutes after the story was published. Mirrors anyone?
about 1 minute and 10 requests...
who the hell is Tony Benn by the way ?
Google passes Turing test : see my journal
Fascinating Read
Life is the leading cause of death in America.
that I will get a +3, funny
Don't waste your vote! Vote for whoever you want, unless you live in a swing state it won't matter anyways
Server timed out trying to contact ex-parrot.com.
Looks like we've got an ex-webserver on our hands.
.
.
"It's not dead, it's IIS!"
Does nobody here on Slashdot even remember the Mythical Man Month any more? The section on estimation and back of the envelope calculations (which I wouldn't be surprised if this blog pulled from, but I can't tell because its slashdotted already) was quite enlightening. Its main point was that people were way too confident in their estimates, even when they would admit that they had no idea.
You're special forces then? That's great! I just love your olympics!
I'll estimate that in about an hour there will be 347 replies posted, about 10 of which will be +5 insightful and, oh, maybe 13 +5 funny.
Oh, yeah, it's not easy to pad these out to 120 characters.
that we'll end up with about 30 comments about how fast the site went down due to slashdotting....
I can usually estimate within plus or minus one or two Libraries of Congress every time.
I actually just finished this book. It's an oldy but goody, and it should be required reading for the statistically challenged. (I.e, those subject to the whims of marketing droids)
Take it easy? I'll take it anyway I can get it . . .
Most folks are 70% correct, at least 30% of the time.
ISP bill this month, but of course, this is only an estimation.
I estimate that at about this point all the jokes about estimating will get tedious
Philip
Signatures are broken
google cache of second link http://216.239.39.104/search?q=cache:DB1CxyRtiNsJ: ex-parrot.com/~chris/wwwitter/20040903-but_i_wore_ the_juice.html+ex-parrot.com+/~chris/wwwitter/2004 0903-but_i_wore_the_juice.html&hl=en&start =1
I'm currently taking a course at my school, for essentially doing computations, but only up to a certain accuracy (estimation with precision). We basically build algorithms, that are normally simple enough to follow, and then just repeat the process until the desired precision is reached. There are multiple ways to do estimation. Like for square roots, you can actually used Fixed Point Iteration(x = g(x)), where g(x) = (x+x/n)/2, where n is the integer of the square root. Just continue that process for about 5 times, and the results are amazing.
je suis parce que j'aime
Reminds me of a bit of training from my army days.
If you have difficulty estimating a distance ( range), divide the distance in two, and try estimating that.
This sounds stupid, but actually works. Well, it worked for me. I'll never forget how I laughed in my head at the suggestion, and my astonishment at it actually working.
Mike.
Part 1
Part 2
I used to work at a small datamining shop. The people there were very bright, some of them quite famous in the fields of statistics, number theory, etc.. One day, we were sitting in the front room of our offices having lunch, chewing the fat, as it were.
At lunches, we would sometimes try to stump our CTO a grey beard who is famous for work in information theory and general genius. We had never succeeded, even with obscure questions in biology "How do Prions work?", physics "What order are the colors of the rainbow, and why?", "How does the Corriolus effect work?", etc. that none of us had any particular knowledge of, and always had to research afterwards to determine the correctness of his answers.
So, I posed the question to the group "How many leaves are on that tree outside the window?" It was a ~30 foot tall, bushy tree in the height of summer. I hoped he'd take the bait.. I thought this was going to be very hard to "get right", and it would even be difficult come up with a plausible answer.
After a few moments, I set off the responses by saying that I thought it easily had 10k leaves, possibly 20k or more.
Everyone gasped. "Oh no! No way..." and then proceeded to offer lower and lower estimates.
The responses started with me and made their way up in the seniority ranks (I was the most junior) all the way up to the CTO. He said "Oh! those kinds of things are notoriously hard to estimate. We typically overestimate grossly in counting things of plentitude. Oh, I don't know. 200?".
Finally we had him. There was no way there were 200 leaves on that tree.
Later, in discussion, a trend became clear. The more senior the person, the more conservative was their response, even to the ridiculous level of our CTO saying a tree in full flush, that he could see right outside of the window, had 200 leaves, when it most plainly had many, many more.
Anyone want to hazard a guess? How many leaves on say, an adult Sycamore (or Maple, Oak, etc.)?
that should be +1, ironic
Don't waste your vote! Vote for whoever you want, unless you live in a swing state it won't matter anyways
The article's slashdotted, so I'm not sure what this is all about. But I've always prided myself on my ability to estimate time and miles. Frequently, I'll look at my watch and find it's, say, 3:00. Some time later I'll estimate that it's 4:22, look at my watch, and find it's 4:20.
Similarly, I will look at the odometer in my car, drive a distance, and guess that it's 10 miles later. Looking down, 10.1.
The best is when you combine them. "How long before we get there?" the wife asks. "About 47 minutes," say I, and 47 minutes later arrive at our destination.
I note this only because most everyone else seems incredibly bad at this. As when someone gives you loose directions to a place like this, "Oh, go about 3 miles, then turn left on Main St." Half a mile later I'm slamming on the breaks 'cause I just past a sign saying "Main St." Or when they tell you it's a 5 minute drive, when it's really 15. Drives me batty.
In short, I estimate that just about everyone sucks at estimating. Funny thing is people always over-estimate distance and under-estimate time.
Yeah, I know everybody is after funny mods, but you don't "estimate" a future event, you predict it.
Estimation is making an educated guess at a quantity without scientifically measuring it, usually with some sort of observation.
"I reckon thats 8 inches long and 2 inches thick."
Prediction is using past experience to state that an event will happen.
Norman Cook's Ode to Sl
The server seems to be slow but eventually responsive, so I got a peek at the results and part of the test.
When Poindexter tried to set up a terror gambling pool to predict terror events, he was relying on something like this-- that collective knowledge would somehow converge on the right answer, or something close enough to be useful.
The results from this survey suggest that that's probably true for something where the guessers/bettors actually have some real knowledge, however deeply buried in their memories it might be, but in areas where people have no information (the GDP), or worse, have been hearing sensationalized opinions (average amount that people get on the dole), they can be not only wildly wrong, but have no idea how wildly wrong they can be.
The terror pool gave me the impression that it was going to collect and integrate the wild ass guesses of its members to somehow develop predictions, but it wasn't clear that anybody would have anything better than WAGs, making it possibly of negative value, rather than providing the collected wisdom that was intended.
A sort of trivial example is if I ask a bunch of people to guess the number of jellybeans in a jar. If I show them the jar, the mean guess will probably be pretty close to the true value. In this case, each person is making an estimate based on seeing the beans and the jar.
If I don't show them the jar, or tell them anything about it, they can only make wild guesses, and I could have a tiny jar with a single jellybean, or a jar the size of the Rose Bowl with however many jellybeans that holds. In this case they're making guesses rather than estimates, and the statistics won't tell you anything about the number of beans in the jar (but may tell you something about how the guessers think of jellybeans and jars).
As almost every single comment up until now talks about personal experiences or makes stupid jokes, I'm going to critique the method he uses to score an answer. From the second link (find a google cache of it to read it) you can see that he treats each answer and estimate of the accuracy of the answer as a single question - you get a single score from both. I think this approach is fundamentally flawed. Why not instead score the guess (with some sort of algorithm like the one he uses) and then score the guess of accuracy by the same method. Then if you want a single number, add the two together. Right now if you guess well and guess your accuracy perfectly, you get zero points. That is completely out of whack. Instead, using my way you score the best possible score when you guess perfectly and perfectly guess your accuracy, and the worst possible score when you guess horribly and horribly guess your accuracy. The scores move between those two extremes rationally too. As he wanted people who guessed zero error (thought their guess was a perfect guess) to get no points, he obviously had an agenda - that people should be penalized for thinking they are perfectly right. In no way is this an unbiased or useful test.
I submitted this story last night, and it didn't get posted.
I guess it depends on if the chute opens or not
They spend a lot of time on grouping. For example What is 97 + 198? I was taught to add 8 and 7, carry the one etc...
They are taught to group the numbers, the instantly recognize that the answer is close to 300, then see how it differs from the 100s. 97 is 3 less, 198 is 2 less. Now add the 3 and 2, getting 5.
The answer is of course 300 - 5, or 295.
I find this method very intuitive.
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
half of the time I'm almost always pretty close to the correct.
Free Scotland!
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?
My blog
On a side note, there are many errors made when newspapers, magazines, etc. estimate numbers. Sometimes they will round values before presenting the final number, causing a huge difference. Or they will give some value like $6,021.50 when some of the values have only two or three significant digits. Or they'll make some hideous stats error such as adding two means together and not weighting the scores appropriately. An excellent book that discusses this is John Allen Paulos' "A Mathematician Reads the Newspaper."
A former co-worker was telling us about some of her tutoring experiences. She was helping some high school kids with the concept of estimation. She looked at the ceiling and said you could estimate that it was about 10 feet high. She told them that "the great thing about estimation is that it doesn't have to be the 'right' answer."
So she pointed a car parked nearby and asked one of the students how far he thought the car was. His reply, "50 gallons."
Incredulous, she said that his answer didn't make sense.
"But that's the great thing about estimation! It doesn't have to be right!"
-- Don't Tase me, bro!
You would be describing the difference between localized perception and overall truth, the essential gap between concept and reality.
For example, I can look at the North American business market and go "Wow! Microsoft owns this market!" because all I see is Windows on the desktops.
But in truth, it is the back-end data servers from a myriad of companies and providers which are entrusted with the critical business information, not the desktop. The desktop is merely an access point and a collection of utilities to help people analyse and format that information.
I do not fail; I succeed at finding out what does not work.
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.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
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.
If you want a vision of the future, imagine a youtube comments section scrolling - forever.
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.
This issue has been studied for many decades in order to help organizations minimize losses on bad bids. Courses are taught on this. I took something like this once. There was an exercise to estimate the number of beans in jar. People's guesses fell along a curve called the binnormal distribution. From this equation you can estimate the best price to offer versus other people's bids in order to ocassionally win and make money at it.
Reminds me of some work done by psychologists Kahneman and Tversky (Kahneman went on to win the nobel prize in economics for different studies). In their studies they had people do things like this (e.g., what year was the constitution adopted by the states). Supplying "anchors" influences your judgement. For example, supplying the anchor that the articles of confederation were ratified in 1781 (I think) would shift the answer toward 1781 compared with the case in which the anchor was that George Washington left office in 1796. The idea is that if you know a.) that the constitution came after the articles of confederation and b.) that the constitution was ratified before Washington left office, you will use specific dates associated with those events to anchor your answer.
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.
"We reject as false the choice between our safety and our ideals." --The American President (20.1.2009)
If you're need quick karma, do the following:
1. Post only to new discussions - those with less than 30 comments.
2. Do not reply to main story - instead reply to the first highly modded post.
3. Quote lots of facts or say something political (but keep it loosely on topic and don't use inflammatory statements or you'll get modded a troll).
4. Make your posts long. Long posts are always "Interesting". It's axiomatic.
This will probably get modded Offtopic but since I've got karma to burn and I know how to get it back - I don't think I really care.
I've made up my mind and now I've got to lie in it.