Official Edexcel S3 thread Wednesday 20 May 2015 Morning [6691]

Hi there guys, has anyone got a markscheme definition to confidence intervals? E.g. 95% or whatever. Thanks!

Hi there guys, has anyone got a markscheme definition to confidence intervals? E.g. 95% or whatever. Thanks!

There's no mark scheme definition because you are never asked to define it (out of context at least) but I can give you my best definition/explanation if you want.

I found an extra IAL paper, albeit sample assessment material. Still probably better practice than standard edexcel papers.

http://qualifications.pearson.com/content/dam/pdf/International%20Advanced%20Level/Mathematics/2013/Specification%20and%20sample%20assessments/IAL%20in%20Mathematics%20SAMS%20WEB%20small%20file.pdf

It's on page 379 of the PDF.

Suggestions for S3 specific best practices regarding accuracy of answers?

It seems the standard 3 sig. figures rule applies most of the time but sometimes it appears not to. I would've assumed this would be from table values but sometimes they have awrt 3sf values.

In every paper I have done awrt to 3 (sometimes 4) dp has applied. I've done the recent papers (2010 -2014) so answers to 4dp are safe. They don't penalise you for being too accurate (with the exception of fraction form), so you can leave as many dp as you wish.

Ah I did not know that one! Thanks, I always assumed you got penalised for giving too many figures as a final answer.

Do they accept it when you add (...) after 3/4 decimal places as well do you know?

I think by doing the ial's/ r papers it makes the normal papers easier at least in my opionion.

I remember your username, you must be have been here for a while.

You going Cambridge or something :d



Thank you very much, I will practice this later.

I salute you sir.

Where can I access the IAL papers?

There is actually a mark scheme definition, it's this: "A 95% confidence interval is an interval within which we are 95% confident mew lies" literally that easy. Can't remember what paper exactly but it definitely came up in a past paper (perhaps before 2005).

That isn't what a 95% confidence interval means?

It means: If we repeat the experiment lots of times, 95% of the time the actual value of $\mu$ will lie in the confidence interval.

That isn't what a 95% confidence interval means?

It means: If we repeat the experiment lots of times, 95% of the time the actual value of $\mu$ will lie in the confidence interval.

Forgive me if I am wrong but aren't these saying the same thing?

Look at exercise 3i in the s3 book question 10b (page 59)

Look at exercise 3i in the s3 book question 10b (page 59)

There is actually a mark scheme definition, it's this: "A 95% confidence interval is an interval within which we are 95% confident mew lies" literally that easy. Can't remember what paper exactly but it definitely came up in a past paper (perhaps before 2005).

That isn't what a 95% confidence interval means?

It means: If we repeat the experiment lots of times, 95% of the time the actual value of $\mu$ will lie in the confidence interval.

You need to include the thing about repeated samples though.