Anyone else have S3 tomorrow? Have any tips of key things to know? This is the one I have been dreading along with P3
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S3 tomorrow! Any tips? watch
- Thread Starter
- 10-06-2004 12:49
- 10-06-2004 12:58
s3 hmmmm. Learn which test to use and when. There's nothing worse than coming out of s3 and everyone else saying they used the two sample test and you've gone and used the paired t test or something, especially as s3 has very high mark questions.
also combining variances, i'm not very good at this but the questions they ask usually require you to find AVar(X) rather than Var (AX) which is A^2Var(X)
can someone give me a quick guide to combining variances and which of the above to use and when please!!
- 10-06-2004 13:33
I think its gonna be quite easy actually
I'm doing edexcel... haven't done t tests... thats like s4/5/6 for edexcel... lol
Tip for the edexcel people is to mermorise all the methods, advantages and disadvantages of all the types of sampling... also learn all the assumptions behind everything... there are too many to type here, but if you look in past papers it always comes up...
combining variances... hmmm... thats quite dodgy... it depends on the question... I think jonas123, you have the right idea... its A x var(X)... only when they say find the variance of 4X+Y or sumthing then you do 4^2 x var(X) + var(Y)... but those questions are quite rare in edexcel... most of the time its just Avar(x)... also remember to divide s.d by root n when doing difference of mean test etc...
also remember to add up the E values when under 5 in goodness of fit tests...
rest is pretty straight forward... just do some practise and im sure you will all do fine
- Thread Starter
- 10-06-2004 16:18
Thanks, Im doing edexcel too tomorrow and I always forget about the columns beong less than 5! Lets hope i dont tomorrow
I can do most topics although the mean hypothesis ones are the most difficult