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PostPosted: Wed Oct 12, 2005 1:54 pm 
My Ds is taking his 1st 11+ this week.I don't really buy into the whole coaching thing but have tried to give him a few pointers on exam technique.
I have told him to leave a minute at the end to guess any questions he hasn't got round to-it is multiple choice format.But I have just been struck by an awful thought -do they deduct marks for incorrect answers (in which case he would be better off just not attempting them ) ?.
He is sitting nfer nelson paper for Ripon .


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PostPosted: Wed Oct 12, 2005 4:42 pm 
No, and good luck to your son


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PostPosted: Mon Oct 17, 2005 9:58 am 
If time is running out, first try to eliminate the obvious wrong answers and then settle for random choice. Usually this helps a lot in Non-Verbal reasoning papers, this technique might also be possible in other subjects too.


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 Post subject: Law of Averages
PostPosted: Mon Oct 17, 2005 4:50 pm 
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Joined: Sun Feb 27, 2005 5:24 pm
Posts: 29
Location: Sale, Cheshire
I attach a copy of the definition of 'Law of Averages' from Wikipedia:-

Law of averages
From Wikipedia, the free encyclopedia.

The law of averages is a lay term used to express the view that eventually, everything "evens out." For example: Two very similar people who drive similar cars in similar circumstances over a long period of time will have roughly the same number of accidents. The more children you have, the more likely you will have an equal division of boys and girls. The longer you flip a coin, the more likely the number of heads and tails will equalise.

The formal mathematical result that supports the law of averages is called the law of large numbers. It states that a large sample of a particular probabilistic event will tend to reflect the underlying probabilities. For example, after tossing a "fair coin" 1000 times, we would expect the result to be approximately 500 heads results, because this would reflect the underlying 0.5 chance of a heads result for any given flip.

However, it is important that while the average will move closer to the underlying probability, in absolute terms deviation from the expected value will increase. For example, after 1000 coin flips, we might see 520 heads. After 10,000 flips, we might then see 5096 heads. The average has now moved closer to the underlying .5, from .52 to .5096. However, the absolute deviation from the expected number of heads has gone up from 20 to 96.

There are common ways to misunderstand and misapply the law of large numbers:

* "If I flip this coin 1000 times, I will get 500 heads results." False. While we expect approximately 500 heads, it is not the case that we will always get exactly 500 heads results. If the coin is fair the chance of getting exactly 500 heads is about 2.52%. Similarly, getting 520 heads results is not conclusive proof that the coin's true probability of getting heads on a single flip is .52

* "I just got 5 tails in a row. My chances of getting heads must be very good now." False. It was unlikely at the beginning that you would get six tails in a row, but the probability of six tails was the same as five tails followed by a head: 1/64. Looking forward after the fifth toss, these probabilities are still equal. The only difference is that there are no other possibilities, so the probability of either outcome is 1/2. This error can be devastating for amateur gamblers. The thought that "I have to win soon now, because I've been losing and it has to even out" can encourage a gambler to continue to bet more.

There are situations in which a very small imbalance in probabilities can lead to a large imbalance in outcomes, contrary to the usual notion of the law of averages. The gambler's ruin is one such scenario.

Ergo : It doesn't matter whether you choose randomly or put all the same answers, the probability on each question is still 1:5 (if it is an A-E answer).


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PostPosted: Mon Oct 17, 2005 7:37 pm 
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if you study the answers given on a multiple choice sheet they appear pretty random - so if you guess randomly you 'may' get them all wrong-however if you answer in a straight line you will probably get some correct

eg correct answers = a c d c b e

random answers= b e c b a d = all wrong

straight line answers aaa etc = 1 correct

bbb etc = 1 correct

ccc etc = 2 correct

ddd etc = 1 correct

eee etc = 1 correct

i have seen enough papers to see that it does work!


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PostPosted: Mon Oct 17, 2005 10:06 pm 
Probabilty for me goes something like this based on seven questions in a section and five choices per question.

First question 0.2 correct (2 out of 10)

Second question 0.2 x 0.2 correct = 0.04 (4 out of 100)

Third question 0.2 x 0.2 x 0.2 correct = 0.008 (8 out of 1000)

Fourth question 0.2 x 0.2 x 0.2 x 0.2 = 0.00016 (16 out of 10,000)

Etc,

However, by eliminating obvious wrong answers you can reduce the odds.

What is definite is that you have a greater probability of getting a question correct if you answer it rather than leaving it out.


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 Post subject:
PostPosted: Tue Oct 18, 2005 10:58 am 
Although I feel it is okay to tell children to guess any questions they can't answer, I think it is risky to teach too much exam technique to 10 or 11 year olds. You have been filling their minds with maths, English, verbal and non verbal reasoning and now you expect them to understand the "Law of Averages"!!

For goodness sake, let them go in and concentrate on answering to the best of their ability - if their best isn't good enough, then so be it. There are other schools, you know, and most children thrive in them. The children that go to these schools are not animals or deviants, they are ordinary children who didn't go to grammar schools. Grammar schools are selective to the point of ridiculous, they select on ability only. So they have some badly behaved, rude and swearing children too.

Some parents seem to think that all grammar school children are angels.


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 Post subject:
PostPosted: Tue Oct 18, 2005 11:19 am 
I doubt it, judging by the attitude of some of the parents! :roll:


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 Post subject: Release the pressure
PostPosted: Tue Oct 18, 2005 1:16 pm 
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Joined: Sun Feb 27, 2005 5:24 pm
Posts: 29
Location: Sale, Cheshire
Of course, all children (and adults) have good and bad in them. No-one is suggesting that any child that doesn't go to Grammar School is anything but ordinary. The important factor surely is that your child is equipped to realise their full potential. One of the most important jobs of a parent or tutor surely is to take pressure off their child rather than increase it - children put enough pressure upon themselves - but at the same time to help them achieve their best, whether this be artistic, athletic or academic?

It may be that grammar schools are highly selective, but then they don't pretend to be anything else! But for some children that kind of education is right and helps them to thrive, just as a less academic education helps other children to thrive.

My whole point with the 'Law of Averages' is not that the child should understand this or even try to calculate the advantage of straight line answering, but to take the pressure off them by allowing them to do it their own way. To be quite honest, whichever method a child uses, it isn't going to make that much difference, because if they have not answered so many questions that this becomes an important issue then they probably aren't coping with the level of work required anyway. However, exam technique is very important for anyone at any stage of their education because it helps to reduce unnecessary panic!


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