The Student Room Group

s1 - PROBABILITY

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Reply 20
i don't know? i would imagine so , and i would think it would effect your PMCC too but i don't acutally know sorry
Reply 21
erm hi. I thought i'd try and explain how coding affects pmcc- it doesn't- NOT AT ALL. But for some strange reason, sxx/syy/sxy is affected. they aren't affected by +/- but are affected by multiplication and division.

I remember it this way: sxx is related to variance. and variance is std dev. squared. so the coding on the values affects sxx as a square. im not sure if im making much sense, so i'll give an example.

syy= 3535237.5

y is coded to h=y/1000


the std dev. would change from say, 300 to 0.3 - although they're very unrealistic i hope u get my point.

shh would then be equal to 3535237.5 divided by 1000 squared--> 3.5352375

hope this helps. i think it's right- i had to figure it out 4rm the mark scheme cos i was never taught it. Good luck tomorrow :biggrin:
Reply 22
http://www.edexcel.com/migrationdocuments/QP%20GCE%20Curriculum%202000/January%202008/6683_01_rms_20080306.pdf

why is question 2)b) for the lower quartile they did not use the formula 1/4(n+1) and as well for upper quartile?

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