Week 5.
In the flash of an eye, it's been 5 weeks since I've started university life. I've been wanting to make this post for awhile but never got about to doing it.. so here I am.
So many people ask - how is uni? how are you handling uni? or other variations to this question.
Well, uni is not quite what I expected, tho I was quite prepared for it. This sounds paradoxical I know, I'll explain.
I expected uni to be tougher than previous education, but more fun, since I am studying things that I WANT to study, not about how positive and negative ions form ionic bonds and memorizing pointless terms like 2,4-dinitrophenylhydrazine that are just cool to say but have zero practical value.
I expected uni to be relatively free, because that was the impression I got from some people. Like, no more fixed lessons from 8am in the morning to afternoon, it's a flexible schedule.
I expected to make alot of friends.. simply because I want to.
Well, uni IS tougher than previous education. And uni is definitely more fun. Learning about circadian patterns, (our sleep cycle), Pavlov's many experiments on Classical Conditioning in more detail and proactive/retroactive interference which affects our memory. I'm virtually never bored when studying.
Flexible? yes. I go to school at different times every single day. And i have no school on tuesdays :)
Make alot of friends? Yea, thanks to camp, I have a regular bunch of people that I can have lunch with or meet up to study and go for lessons together with.
What was contrary to my expectations was the 'relatively free' part. Being in Arts, the amount of readings we have to do is insane. Imagine an upper secondary Biology textbook, covered over 2 years. The Psych textbook is twice (or more) that size, and is covered in 12 weeks or so.
I'm not even taking many content heavy subjects.. only Psych is heavy for me.
I am studying during virtually all my breaks in school, and my 'free days' of tuesday and weekends are spent studying too. It's like, mugfest.
And the annoying thing is, my circle of friends all tell me that i'm 'too mugger', that i 'study too much la!' . But it's not like i'm doing EXTRA or anything.. I just do the week's assigned readings. To them, lagging behind is the norm.
K wait that's not the annoying thing.. the annoying thing is, even though I study so much, it's very possible that I will not do better than all of them, because
1) Modules are marked on a bell curve, so let's say I do pretty well in all my modules but those taking my modules do EVEN BETTER.. my grades will become shit.
2) The modules other people take may consist of all slackers or something, so getting an A may be very easy.
3) Thus, their CAP will be better than me.
Ok i know this is a faulty conclusion due to the faulty reasoning #2, but another matter is that amount of studying does not necessarily lead to better grades. If I am not able to apply what I have learnt to the questions in the exams, it will come to naught.
So really, all i hope for is that my grades will reflect the amount of effort I put in. Because I am perpetually tired with all this studying, my sleep isn't very sound because I'm always worrying (or rather, thinking) about what I'll be doing the next day
etcetc.
Because if at the end of the day I get a decent CAP (above 4, as close to 5 as possible) I will feel it's worth it. The hard work I put in, the endless hours I spent studying, all this - it's all worth it.
If i DONT.... I think I'll just feel like shit. Like fmd, wasting my time studying so hard.
Alright, just wanted to pen that down. If you are really reading all this.. I'm honoured that you're so interested in my life. je t'aime, tres tres t'aime!
a bientot~
Wednesday, 8 September 2010
Friday, 3 September 2010
mrbrown does it again
Lol this is funny shit.
context:
PM Lee announces in National Day Rally that NSMen will be getting 9k (10k for commanders) in 3 phases. However, this only applies for those who have not finished their 10 cycles of reservist. Those who finished, ('ROD'ed) they wont be getting this payouts.
[youtube http://www.youtube.com/watch?v=oZpQmYO8S5s&fs=1&hl=en_US]
context:
PM Lee announces in National Day Rally that NSMen will be getting 9k (10k for commanders) in 3 phases. However, this only applies for those who have not finished their 10 cycles of reservist. Those who finished, ('ROD'ed) they wont be getting this payouts.
[youtube http://www.youtube.com/watch?v=oZpQmYO8S5s&fs=1&hl=en_US]
Monday, 30 August 2010
negative marking
*made some important changes in 5-6 guesses*
Ok so for this module in my school, they employ this marking scheme for the MCQ exam called 'negative marking'. What this basically means is that for every correct answer we will get 1 mark, every wrong answer we will get -0.25 marks, and every blank we will not get any marks (or get 0 marks)
So comes the following question:
Would it better to leave any unsure questions blank, or simply guess all of them?
There should be a mathematical answer based on probability, so I shall set out to find this solution.
(all based on a 4-answer-choices MCQ)
The Basic Assumption
There is a basic assumption which we must make before we proceed, that is, there is a 1 in 4 chance of getting 1 mark, or 1/4 chance of getting 1 mark.
Some may be quick to point out that there are five options here, that is, 1 correct answer and 3 correct answers, AND the option of leaving it blank. Shouldn't it be 1/5?
The answer to that is simple, since leaving it blank is a definite 0 marks,(i.e. when you leave it blank, you KNOW for sure it is 0 marks, it is not a 1/5 chance that you will get 0 marks) it should be automatically excluded from the probabilities.
So with this basic assumption in mind, let's proceed.
Analysis
It is noteworthy that all the examples will just be weighing if it's better to guess all or to leave them all blank. They will not consider a 'mixture' of guessing and leaving blank, since that is a separate matter altogether.
So with the 1/4 assumption, it follows that
- for every 4 guesses, you will get 1 correct.
Since the 4 guesses are for 4 random questions, this has to be correct; it is mathematically sound.
Let's start with a simple example, there are only 4 unsure questions and hence only 4 guesses you make in the paper.
4 guesses - 1 correct, 3 wrong
-> +(1x1) -(3x0.25) = +0.25
Thus, more beneficial to guess all.
How about 5 guesses? This would be slightly more complicated, since 1/4 of 5 is 1.25, and rounding up or down would result in an inaccurate answer.
To get a round number, we take a group of 4 people with 5 guesses each. Thus 'getting 0.25 correct' means out of a group of 4 people, 1/4 of them will get it right (means they have TWO correct) while the other 3/4 of them will get only one right.
[Read the explanation in these square brackets if you don't get why it's 3/4 will only get 1 right.
Let's simplify matters to just 4 people having 1 guess each. If they each have a 0.25 chance of getting it right, it means 1 out of 4 will get it right.
So why that 1/4 group in the example above gets TWO correct is because their odds state they will get the 1st '1' correct, just that the 2nd '0.25' is up for probability]
Thus for 5 guesses, there's a 1/4 chance we will get 2 correct (better to just guess all)
and there's a 3/4 chance we will only get 1 correct (better to just leave all blank, as 1 correct in 5 means +1 -1.25 = -0.25)
Therefore, for 5 guesses, there is a higher probability that you will get a negative mark than a positive mark for guessing.
HOWEVER. What you should do here is to leave 1 of them blank (to guarantee 0 marks, no negative), and guess the other 4 (which will be the same case as 4 guesses, which is beneficial as shown earlier.)
6 guesses will follow the same logic, leave 2 blank, and guess 4.
7 guesses onwards it is more beneficial to go for the +0.75 (you have a higher probability anyway) than to settle for the +0.25 of 4 guesses, 3 blank. Thus:
7 guesses (instead of 7 blanks) will result in a higher chance of getting +0.75 than the negative case (work it out yourself), same for 8 and 9 guesses.
10 guesses is another 50/50 chance as in the 6 guesses case, but this time it's either a positive or neutral (0 net marks) result, so it's better to take your chance and guess them all too.
And by further deduction you can see that subsequent greater number of guesses will always result in a higher probability of getting a positive mark. Thus for 7 guesses and above, it is more beneficial to guess all than to leave all blank.
Now let's take a step back and examine the last 3 numbers which we did not look at - 1, 2 and 3 guesses.
1 guess
You have a 1/4 chance of getting 1 mark, and a 3/4 chance of losing 0.25 marks. It's a no-brainer, better to just leave it blank and guarantee no negation since the negative result has a higher probability.
2 guesses
We have to look at this in the case of multiple participants again, since 0.25 x 2 = 0.5
So out of 2 participants, it follows that either one will get it correct. It's another 50/50 case.
50% -> You get 1 mark
50% -> You lose 0.25 marks
This is the only ambiguous case, where the advantage of securing '0 points' by not guessing at all is not clear.
3 guesses
0.25 x 3 = 0.75
Which follows that there is a higher probability that you will be in the group that gets 1 /3 correct (3/4 chance to be exact) which is a +1 - 0.5 = +0.5 benefit, hence it is better to guess all for 3 guesses.
Summary
If you have 1 unsure question, it is more beneficial (or mathematically sound) to leave it blank.
If you have 3,4 unsure, guess them all.
If you have 5 or 6 unsure, leave blank 1 or 2 respectively, and guess the remaining 4.
If you have 7 or more unsure questions, it is more beneficial (or mathematically sound) to guess them all.
If you have 2 unsure.. flip a coin to decide whether you should guess or not, as there is no clear mathematical advantage on either side.
P.S.
Weiqin did a binomial calculation that more or less supports my noob calculations
http://i136.photobucket.com/albums/q166/atqhteo/31082010336.jpg
http://i136.photobucket.com/albums/q166/atqhteo/31082010337.jpg
ENJOY :D
Ok so for this module in my school, they employ this marking scheme for the MCQ exam called 'negative marking'. What this basically means is that for every correct answer we will get 1 mark, every wrong answer we will get -0.25 marks, and every blank we will not get any marks (or get 0 marks)
So comes the following question:
Would it better to leave any unsure questions blank, or simply guess all of them?
There should be a mathematical answer based on probability, so I shall set out to find this solution.
(all based on a 4-answer-choices MCQ)
The Basic Assumption
There is a basic assumption which we must make before we proceed, that is, there is a 1 in 4 chance of getting 1 mark, or 1/4 chance of getting 1 mark.
Some may be quick to point out that there are five options here, that is, 1 correct answer and 3 correct answers, AND the option of leaving it blank. Shouldn't it be 1/5?
The answer to that is simple, since leaving it blank is a definite 0 marks,(i.e. when you leave it blank, you KNOW for sure it is 0 marks, it is not a 1/5 chance that you will get 0 marks) it should be automatically excluded from the probabilities.
So with this basic assumption in mind, let's proceed.
Analysis
It is noteworthy that all the examples will just be weighing if it's better to guess all or to leave them all blank. They will not consider a 'mixture' of guessing and leaving blank, since that is a separate matter altogether.
So with the 1/4 assumption, it follows that
- for every 4 guesses, you will get 1 correct.
Since the 4 guesses are for 4 random questions, this has to be correct; it is mathematically sound.
Let's start with a simple example, there are only 4 unsure questions and hence only 4 guesses you make in the paper.
4 guesses - 1 correct, 3 wrong
-> +(1x1) -(3x0.25) = +0.25
Thus, more beneficial to guess all.
How about 5 guesses? This would be slightly more complicated, since 1/4 of 5 is 1.25, and rounding up or down would result in an inaccurate answer.
To get a round number, we take a group of 4 people with 5 guesses each. Thus 'getting 0.25 correct' means out of a group of 4 people, 1/4 of them will get it right (means they have TWO correct) while the other 3/4 of them will get only one right.
[Read the explanation in these square brackets if you don't get why it's 3/4 will only get 1 right.
Let's simplify matters to just 4 people having 1 guess each. If they each have a 0.25 chance of getting it right, it means 1 out of 4 will get it right.
So why that 1/4 group in the example above gets TWO correct is because their odds state they will get the 1st '1' correct, just that the 2nd '0.25' is up for probability]
Thus for 5 guesses, there's a 1/4 chance we will get 2 correct (better to just guess all)
and there's a 3/4 chance we will only get 1 correct (better to just leave all blank, as 1 correct in 5 means +1 -1.25 = -0.25)
Therefore, for 5 guesses, there is a higher probability that you will get a negative mark than a positive mark for guessing.
HOWEVER. What you should do here is to leave 1 of them blank (to guarantee 0 marks, no negative), and guess the other 4 (which will be the same case as 4 guesses, which is beneficial as shown earlier.)
6 guesses will follow the same logic, leave 2 blank, and guess 4.
7 guesses onwards it is more beneficial to go for the +0.75 (you have a higher probability anyway) than to settle for the +0.25 of 4 guesses, 3 blank. Thus:
7 guesses (instead of 7 blanks) will result in a higher chance of getting +0.75 than the negative case (work it out yourself), same for 8 and 9 guesses.
10 guesses is another 50/50 chance as in the 6 guesses case, but this time it's either a positive or neutral (0 net marks) result, so it's better to take your chance and guess them all too.
And by further deduction you can see that subsequent greater number of guesses will always result in a higher probability of getting a positive mark. Thus for 7 guesses and above, it is more beneficial to guess all than to leave all blank.
Now let's take a step back and examine the last 3 numbers which we did not look at - 1, 2 and 3 guesses.
1 guess
You have a 1/4 chance of getting 1 mark, and a 3/4 chance of losing 0.25 marks. It's a no-brainer, better to just leave it blank and guarantee no negation since the negative result has a higher probability.
2 guesses
We have to look at this in the case of multiple participants again, since 0.25 x 2 = 0.5
So out of 2 participants, it follows that either one will get it correct. It's another 50/50 case.
50% -> You get 1 mark
50% -> You lose 0.25 marks
This is the only ambiguous case, where the advantage of securing '0 points' by not guessing at all is not clear.
3 guesses
0.25 x 3 = 0.75
Which follows that there is a higher probability that you will be in the group that gets 1 /3 correct (3/4 chance to be exact) which is a +1 - 0.5 = +0.5 benefit, hence it is better to guess all for 3 guesses.
Summary
If you have 1 unsure question, it is more beneficial (or mathematically sound) to leave it blank.
If you have 3,4 unsure, guess them all.
If you have 5 or 6 unsure, leave blank 1 or 2 respectively, and guess the remaining 4.
If you have 7 or more unsure questions, it is more beneficial (or mathematically sound) to guess them all.
If you have 2 unsure.. flip a coin to decide whether you should guess or not, as there is no clear mathematical advantage on either side.
P.S.
Weiqin did a binomial calculation that more or less supports my noob calculations
http://i136.photobucket.com/albums/q166/atqhteo/31082010336.jpg
http://i136.photobucket.com/albums/q166/atqhteo/31082010337.jpg
ENJOY :D
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