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Edexcel S3 - Wednesday 25th May AM 2016

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Original post by economicss
Just to check, if one our expected frequencies came out to 5 exactly, this wouldn't be combined right, we only combine values less than 5?! Thanks :-)


this is fine, i wouldn't group it with another colomn etc
Can someone make an S2 thread as well?
Is maximum likelihood estimators a part of S3 or S4?
Original post by ServantOfMorgoth
Is maximum likelihood estimators a part of S3 or S4?


Not as far as I am aware.

All you need to do is find the joint distribution of all of the observations in terms of the parameter, xi, log it if necessary, differentiate it with respect to the parameter and solve that, before differnetiating again to check that it is a maximum. Slightly more complicated if it involves two parameters.

Original post by Ayman!
Can someone make an S2 thread as well?


If no one else has, I can try :tongue:
Original post by SeanFM
If no one else has, I can try :tongue:


Sean, you're back! Where have you been? And go ahead if it's not too much trouble :biggrin:
Original post by SeanFM
Not as far as I am aware.

All you need to do is find the joint distribution of all of the observations in terms of the parameter, xi, log it if necessary, differentiate it with respect to the parameter and solve that, before differnetiating again to check that it is a maximum. Slightly more complicated if it involves two parameters.


So it isn't an a level topic?
Original post by ServantOfMorgoth
So it isn't an a level topic?


Not as far as I am aware, for Edexcel at least.

Original post by Ayman!
Sean, you're back! Where have you been? And go ahead if it's not too much trouble :biggrin:


Uni work :hide: :bricks: :work:
Original post by SeanFM
Not as far as I am aware, for Edexcel at least.




The derivation for the normal distribution MLE for the mean is very confusing.
Original post by ServantOfMorgoth
The derivation for the normal distribution MLE for the mean is very confusing.


Which part? This page seems to explain it okay, I think.
Original post by SeanFM
Which part? This page seems to explain it okay, I think.


I closed that exact same page a few mins ago. I'm not required to know how to derive for 2 unknowns and they don't have an example with only the mean.
Original post by ServantOfMorgoth
I closed that exact same page a few mins ago. I'm not required to know how to derive for 2 unknowns and they don't have an example with only the mean.


I think you can just treat sigma as a constant and use what they've done for the mean.
Original post by SeanFM
I think you can just treat sigma as a constant and use what they've done for the mean.


Haha yeah, I figured it out. Thanks
Reply 132
https://ee3a68c993d24792ee12a4f9f9608588558306b5.googledrive.com/host/0B1ZiqBksUHNYeklwX3hHSnNPTVE/for-Edexcel/Solomon%20E%20QP%20-%20S3%20Edexcel.pdf

Everything is fine for the very last part of the last question except I used a continuity correction but the mark scheme doesn't use this. Why is this?
I did it slightly differently where I would Reset the Q to P(no of sixes is more than 180)
Then I did P(X1+...+X100>180.5) I rechecked if I had just done P(X1+...X100>180) then I would have got the correct answer.
(edited 7 years ago)
I'm a statistics expert in S1- 4 now. Thanks uni :rolleyes:

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Original post by Rkai01
https://ee3a68c993d24792ee12a4f9f9608588558306b5.googledrive.com/host/0B1ZiqBksUHNYeklwX3hHSnNPTVE/for-Edexcel/Solomon%20E%20QP%20-%20S3%20Edexcel.pdf

Everything is fine for the very last part of the last question except I used a continuity correction but the mark scheme doesn't use this. Why is this?
I did it slightly differently where I would Reset the Q to P(no of sixes is more than 180)
Then I did P(X1+...+X100>180.5) I rechecked if I had just done P(X1+...X100>180) then I would have got the correct answer.


You don't need to use a continuity correction after using in the central limit theorem in Edexcel S3
Original post by Rkai01
https://ee3a68c993d24792ee12a4f9f9608588558306b5.googledrive.com/host/0B1ZiqBksUHNYeklwX3hHSnNPTVE/for-Edexcel/Solomon%20E%20QP%20-%20S3%20Edexcel.pdf

Everything is fine for the very last part of the last question except I used a continuity correction but the mark scheme doesn't use this. Why is this?
I did it slightly differently where I would Reset the Q to P(no of sixes is more than 180)
Then I did P(X1+...+X100>180.5) I rechecked if I had just done P(X1+...X100>180) then I would have got the correct answer.


The continuity correction is only for when you do the approximations

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Reply 136
Original post by Ayman!
You don't need to use a continuity correction after using in the central limit theorem in Edexcel S3


In the book it does say a continuity correction can be applied depending on a question. It is definitely in the chapter 3 somewhere in a red box where they write comments.
Reply 137
Original post by ServantOfMorgoth
The continuity correction is only for when you do the approximations

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But it is an approximation? We are going from binomio to normal
The june 2015 paper is beautiful.
Original post by Rkai01
But it is an approximation? We are going from binomio to normal


But you have already used Central linit theorem.


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