Hypothesis Test Using PMCC

Question 1

Wait what is a SAMPLE PMCC, where did this come from?

Answer 1

When using data to work out a PMCC often it came from a LARGE parent data set, that has been SAMPLED from

Thus any conclusions from your data my not NECESSARILY mean the same thing for the real parent

Question 2

Why may sample not be like parent

Answer 2

Because parent could be negative and your sample is positive, so it won’t work

Question 3

So what’s the hypothesis test essentially we doing?

Answer 3

We calculating PMCC from sample, and DETERMINING if this is enough to CONVINCE us the trend is the same for thr parent, this is thr sample PMCC hypothesis test we trying to do

Question 4

When they mean sample from parent give a context scenario

Answer 4

Just like you csn’t measure all fish in sea, yiu measure a bit, find a correlation but now you want to see if this will be same for everythign rlse

Question 5

What is the significance level again DEFINITION

Answer 5

The probaiolty of rejecting the null hypothesis when it is ACTUALLY TRUE

Thus the lower the significance level, the better reliability, but less chance of a positive result

So need to balance significance level , but exam question might ask to discuss

Question 6

What was 1 tail vs 2 tail again

Answer 6

1 tail is one direction only, positbe or negative correlation

2 tail is if there is some correaltion or any

Question 7

Remember what To do with PMCC at the end to compare with fro tail value

Answer 7

Find the MOD. Of it. If it’s bigger, reject H0!

Question 8

HOW TO DO CONCLUSIVE STATEMENT

Answer 8

Don’t go and make new statement, if you reject, then say there is INSUFFIECNET EVIDECEN TO SUGGEST whatever tedt was for

And if it is accept, say sufficient evidence to suggest there is whatever test saud for

Question 9

What if they give you a P VALUE, and all you have is significance what to do
IMPORTANT

Answer 9

Carry out hypothesis test as normal
- if it is a 2 tail test, HALF SIGNFINICANVE VALUE, if not keep same
- NOW COMPARE P TO SIG VALUE

If P value is LESS THAN SIGNIFICANCE, reject

Question 10

What’s the problem we face with LARGE samples from a parent and thus why do we use effect size

Answer 10

Large samples, the critical value becomes very small, and so it’s easy ti by chance find evdiecen to reject h0, when we shouldn’t

Thus effect size vs,use allow us to interpret PMCC for large data sets

Question 11

So if I calculate large sample of data PMCC and it’s 0.5 what tries it mean

Answer 11

Using effect size graph, it means it’s a large effect, so string correeltiwon, even tho before wr said 0.8 and Above was STROng