Edexcel S3 - Wednesday 25th May AM 2016

I lost it when the eigenvalues were really weird...couldn't believe I'd done it right and kept looking for a mistake then I just left or barely bothered with half the proofs properly lol. Dropped like a dozen marks

For Spearman's RCC, how are 'Tied Ranks' supposed to be dealt with?

Also, is it fine to write:

$H_0:$ There is no correlation between X and Y

Rather than:

$H_0: \rho = 0$

bump

You should put it in terms of Roh, the mark schemes are really strict about this :s

bump

You should put it in terms of Roh, the mark schemes are really strict about this :s

You should put it in terms of Roh, the mark schemes are really strict about this :s

what is roh the greek latter xD

Thanks again

$\rho$ - this thingamabob



No worries, man!

Does anyone know what we have to do when we have tied ranks? Is it just "average ranks and use PMCC"?

$\rho$ - this thingamabob

It's rho, not roh.

Does anyone know what we have to do when we have tied ranks? Is it just "average ranks and use PMCC"?

Yes exactly what you said. If you go on the Solomon papers (B i think) there's a question like that that asks "what would you do if the price for B and F (or some other letters) was the same" and the answer is to use average ranks then use PMCC

What does it mean by 'average ranks' and then use product moment correlation coefficient? (I assume that's PMCC)

If you have B and rank 6 and F at rank 7 and the question if i remember correctly it said the price of B and F is now the same so you'd rank them 6.5 each and then figure out Sxx and Syy and Sxy and then use PMCC.

can someone explain part d)? its from the June 15 paper

can someone explain part d)? its from the June 15 paper

It's saying that you need to say two things: 1. In the individual strata, the variances are small. 2. In the combined thing, the variances are large since the difference of means are large meaning the overall variances from the overall mean are large.

can someone explain part d)? its from the June 15 paper

I can't remember what the answer is or how to get it, but it's the most stupid question in S3 that I have ever seen.

How come? It's actually a valid question that isn't stupid sampling crap.

$\rho$ - this thingamabob



No worries, man!

Does anyone know what we have to do when we have tied ranks? Is it just "average ranks and use PMCC"?

What does it mean by 'average ranks' and then use product moment correlation coefficient? (I assume that's PMCC)