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# Edexcel S1 - 15th June, 2016 [Exam Discussion] watch

1. I read on another thread (link: http://www.thestudentroom.co.uk/show...949172&page=15) that if the mean is 50 and the coding is x/10 the mean becomes 0.5- but is that true?
2. (Original post by tazza ma razza)
mate - this has been asked countless times - I can't recollect there being an answer tho ahaha Have you checked the textbook?
sorry I just got back from chemistry and do S1 straight away so havent check, that case was like an extra number added, but what if we code like v=x/1000, would it matter ??
3. (Original post by siamesedaffodil)
Using a venn diagram..

...how would you work out P(A' U B) and P(A' U B'?? ? ?

Thanks!!

P(A u B) = P(A) + P(B) - P(A n B)

It's often easier to visualise intersections rather than unions so use this if you're stuck.
4. (Original post by physicsamor)
Good luck everyone I'm done for the day. Just try your best
thanks good luck to you too!
5. (Original post by anndz3007)
sorry I just got back from chemistry and do S1 straight away so havent check, that case was like an extra number added, but what if we code like v=x/1000, would it matter ??
I'm so confused, because apparently they're all different for Sxx, Syy and Sxy
6. Can someone please list all the things that can be coded and explain effect of coding on each of these things?
7. (Original post by hogree)
So, say you have 60 values. You want to work out the lower quartile. Do n/4 ---> 6/4 -----> 15. So you use the 15.5th value.
Okay, but when I find the Q2, it's 60/4 which is 30, so I find the average of the 30th and 31st value?
8. (Original post by hogree)
So, if you have a Coding where of say 2X+6, you ignore the +6. You multiply the Sxx by 4 (because that's 2^2), You multiply the Sxy by 2, and you don't multiply the Syy. That's what I saw from someone else. PMCC remains the same always.

Yes, that would be an example of when you would use that method.
So Sxx = multiply by n^2
Sxy = multiply by n
Syy = no effect

Also are you 100% certain because I cant find much regarding this?
9. (Original post by hogree)
So, if you have a Coding where of say 2X+6, you ignore the +6. You multiply the Sxx by 4 (because that's 2^2), You multiply the Sxy by 2, and you don't multiply the Syy. That's what I saw from someone else. PMCC remains the same always.

Yes, that would be an example of when you would use that method.
so like if you got x=2a+6, Sxx= 4 Saa, y=4b+1, Syy= 16 Sbb , and Sxy= (2x4=8) Sab ?? just checked it in one example and it didnt turn out right
10. Anyone got any predictions for tommorw??
11. (Original post by Mina_)
So Sxx = multiply by n^2Sxy = multiply by nSyy = no effectAlso are you 100% certain because I cant find much regarding this?
I cannot claim I am 100% certain. But I have seen a couple of people say this. Is there an example Question anywhere?
(Original post by Uberphuq)
Okay, but when I find the Q2, it's 60/4 which is 30, so I find the average of the 30th and 31st value?
That's exactly right. An example of this being used in Question 2 of Jan 2008.

(Original post by anndz3007)
so like if you got x=2a+6, Sxx= 4 Saa, y=4b+1, Syy= 16 Sbb , and Sxy= (2x4=8) Sab ?? just checked it in one example and it didnt turn out right
I think that is right. Could I have a look at the example?
12. (Original post by hogree)
I cannot claim I am 100% certain. But I have seen a couple of people say this. Is there an example Question anywhere?That's exactly right. An example of this being used in Question 2 of Jan 2008.

I think that is right. Could I have a look at the example?
https://1a388b28f5ce9318f837a64962fc...%20Edexcel.pdf

question 2, if you try to find d= Svs/Sss, you would not get the value as shown ??

Edit: It actually works, sorry its just me messing with Sxx Sxy value
13. Can you use a black rollergel pen?

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14. (Original post by Mina_)
So Sxx = multiply by n^2
Sxy = multiply by n
Syy = no effect

Also are you 100% certain because I cant find much regarding this?

so like if you got x=2a+6, Sxx= 4 Saa, y=4b+1, Syy= 16 Sbb , and Sxy= (2x4=8) Sab

Checked and it work, if only x is coded, Syy does not change, if both coded, they both would change
15. [QUOTE=jessyjellytot14;65785699]Can you use a black rollergel pen?

It says no gel pens on the exam so i highly doubt it. I use the Uni-ball Eye ink pens as the flow similar to gel pens
16. (Original post by SweetChilliCake)
y=0.746+0.102x
Also how do you do the last part of that question. I never understand them
17. (Original post by anndz3007)
so like if you got x=2a+6, Sxx= 4 Saa, y=4b+1, Syy= 16 Sbb , and Sxy= (2x4=8) Sab

Checked and it work, if only x is coded, Syy does not change, if both coded, they both would change
Sorry but what are you on about
18. (Original post by anndz3007)
https://1a388b28f5ce9318f837a64962fc...%20Edexcel.pdf

question 2, if you try to find d= Svs/Sss, you would not get the value as shown ??

Edit: It actually works, sorry its just me messing with Sxx Sxy value
Yup it works. That's definitely the way to Code Regression. Fab
19. (Original post by thelegend99)
hogree
whoops hogree if events are independent, does that meant they're linked (does one affect the other)? Saw an example with two children being late.
20. (Original post by Zacken)
No problem.
So i stalked your profile and saw you insured warwick over imperial. Why?

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