S3 - June 2014 Exam Prep Question

Hi everyone; I just wanted to ask a question regarding S3 in preparation for the exam on Thursday and start a thread about it to talk after too!
It's quite a specific question about the replacement paper for 2013 June S3 last year. If you haven't done it, I think its a good one to do for Thursday, quite challenging!
The link is here to the paper:
https://googledrive.com/host/0B1ZiqBksUHNYVGVDMmVJYzVnRnc/June%202013%20(R)%20QP%20-%20S3%20Edexcel.pdf
And to the mark scheme:
https://googledrive.com/host/0B1ZiqBksUHNYVGVDMmVJYzVnRnc/June%202013%20(R)%20MS%20-%20S3%20Edexcel.pdf

On question 4 when we are asked to test the hypothesis about proportion of hair colors, personally I calculated the (observed-expected)^2/expected test statistic for all 4 rows, and had a degree of freedom of 15. In the mark scheme they just did the totals, and although we came out with the same result, I feel their method of only using totals disregarded a lot of data? Any advice about the best method, and I'm really interested to know if you think I would get the marks for doing it my way.

Thanks for any advice, and good luck for the exam!!

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Reply 1

EL77

Was this paper the one that candidates actually sat?

Reply 2

Dorrez2k12

Yeah, so there was two papers. Some sat the replacement, and some the other normal paper. I think it is to do with the original paper being leaked. It happened with all models

Reply 3

mahatma ghandi

Original post by Dorrez2k12

I did it the same way that is written in the mark scheme, I don't really see how you think it disregarded a lot of data, since every value is used in the calculation. As far as I can tell no data has being disregarded. But obviously the method you chose to use worked for you so my advice would be to continue doing what you're comfortable with in the exam, there's more than one route of getting to the answer. For the same paper, I don't really understand question 6a), any chance you could try and explain it to me?

Reply 4

Dorrez2k12

Thanks for the response!
I hope this helps in answer to your question

image.jpg530.9KB

Reply 5

Giant

Original post by Dorrez2k12

On question 4 when we are asked to test the hypothesis about proportion of hair colors, personally I calculated the (observed-expected)^2/expected test statistic for all 4 rows, and had a degree of freedom of 15. In the mark scheme they just did the totals, and although we came out with the same result, I feel their method of only using totals disregarded a lot of data? Any advice about the best method, and I'm really interested to know if you think I would get the marks for doing it my way.

Thanks for any advice, and good luck for the exam!!

Just did this paper, you're right it was quite challenging.

The question states for you to only use Table 1 - so you essentially ignore all the stuff about eye colours and focus on the hair colours. From this you get your observed values as 105, 282, 48 and 165 respectively. Using the ratios they give, you can calculate your Expected values (100,300,50,150) and then use the normal method. There are only 3 degrees of freedom (4 parameters and 1 constraint)

It was definitely a question that required you to thing outside the box - you just need to ignore all irrelevant information (eye colours) and focus on the distribution they're asking you to test.

I doubt that tomorrow's paper will be as difficult as this, however.

Reply 6

ptvrk

on june 2013 replacement paper, on question 4, can anyone explain to me why the null and alternative hypotheses were written like that? Its because every other past paper ask you about association.
Thanks

Reply 7

mahatma ghandi

Original post by Dorrez2k12

Thanks for the response!
I hope this helps in answer to your question

Thanks that's very helpful

Reply 8

Gillerz

How did everyone find it?

Reply 9

Dorrez2k12

Can we talk about it?

Reply 10

Vilhelmschofield

We've got to wait 24 hours, so all im saying is that I was quite pleased. A few dodgy definition questions and weird mean and variance questions but overall, happy. Quite similar to most past papers.

Reply 11

Geniusguy

Original post by Vilhelmschofield

We've got to wait 24 hours, so all im saying is that I was quite pleased. A few dodgy definition questions and weird mean and variance questions but overall, happy. Quite similar to most past papers.

Nope, you're welcome to discuss it straight away, TSR introduced new rules the other day meaning that we can discuss the exam as soon as it has finished, provided we don't post a full unofficial mark scheme until 24 hours have passed.

More info here:

http://www.thestudentroom.co.uk/showthread.php?t=2686937

Reply 12

Geniusguy

Original post by Dorrez2k12

Can we talk about it?

Yes, I found it quite a good paper on the whole, that defining statistics question was a bit annoying though, I put yes, no, no respectively for the three, did anyone else get that?

Reply 13

Dorrez2k12

Yeah I thought it went quite well too. The only thing I think I did wrong was forgot to square the 2 on the bottom of the statistic fraction when calculating the variance :-((( besides that pretty standard :smile: