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i just have a quick query to do with Regression.. I've done correlation so I know the concepts just bit confused..

*basically i've got a mock on it tommorrow can someone explain how to get the mean of y(bar) or something along them lines.. or can someone just sumarize the chapter (send me a link) as I can't find any online*
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#2

(Original post by

i just have a quick query to do with Regression.. I've done correlation so I know the concepts just bit confused..

**Coerce**)i just have a quick query to do with Regression.. I've done correlation so I know the concepts just bit confused..

*basically i've got a mock on it tommorrow can someone explain how to get the mean of y(bar) or something along them lines.. or can someone just sumarize the chapter (send me a link) as I can't find any online*
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I think you mean the average of y. To find y(bar), add all the values of y, then divide by the number of values. In an exam, they will usually give y(bar) though instead of giving sample data.

**morgan8002**)I think you mean the average of y. To find y(bar), add all the values of y, then divide by the number of values. In an exam, they will usually give y(bar) though instead of giving sample data.

I'm just confused what is the difference between Regression and Correlation?

Except that its to do with y= a +bx and b = sxy/sxx -- which you get in the formula book?

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How stupid of me.. ofc I ddn't mean to write it like that I know how to work a mean out. haha!

I'm just confused what is the difference between Regression and Correlation?

Except that its to do with y= a +bx and b = sxy/sxx -- which you get in the formula book?

**Coerce**)How stupid of me.. ofc I ddn't mean to write it like that I know how to work a mean out. haha!

I'm just confused what is the difference between Regression and Correlation?

Except that its to do with y= a +bx and b = sxy/sxx -- which you get in the formula book?

A regression line is a linear line of the form y = a + bx or y = ax + b, which allows you to estimate y for other values of x or x for other values of y.

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Product moment correlation coefficient is a number between -1 and 1. The modulus(size) of the coefficient gives correlation, the sign tells you whether an increase in x causes an increase or decrease in y.

A regression line is a linear line of the form y = a + bx or y = ax + b, which allows you to estimate y for other values of x or x for other values of y.

**morgan8002**)Product moment correlation coefficient is a number between -1 and 1. The modulus(size) of the coefficient gives correlation, the sign tells you whether an increase in x causes an increase or decrease in y.

A regression line is a linear line of the form y = a + bx or y = ax + b, which allows you to estimate y for other values of x or x for other values of y.

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Ignore what I just said.. I realized you get given a table and just work out B (sxy/sxx) and A = ybar - bxbar and im so stupid for stressing and forgetting it all sorrry

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#7

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Oh so the aim is to basically work that out.. how do you work out A or X? I think I need to get some coffee just woken up

**Coerce**)Oh so the aim is to basically work that out.. how do you work out A or X? I think I need to get some coffee just woken up

It may also ask you to find the equation of the regression line(same data) and you just find the values of a and b. It may then give you a particular value of x and ask you to estimate the value of y at this point. Just substitute the value of x into the equation you just found to find the value of y.

edit: seriously it's 9pm!

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#8

all of the ax + b details can be worked out by pretty much any calculator nowadays... it is worth finding out how on yours.

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#9

Another thing to note is that when using the regression line to estimate values, if it's within the range given, it is called interpolation. If it's outside of the range it is called extrapolation and is less reliable. Questions may ask you to comment on the reliability and you answer with either one of these for one mark.

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(Original post by

all of the ax + b details can be worked out by pretty much any calculator nowadays... it is worth finding out how on yours.

**the bear**)all of the ax + b details can be worked out by pretty much any calculator nowadays... it is worth finding out how on yours.

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(Original post by

Another thing to note is that when using the regression line to estimate values, if it's within the range given, it is called interpolation. If it's outside of the range it is called extrapolation and is less reliable. Questions may ask you to comment on the reliability and you answer with either one of these for one mark.

**morgan8002**)Another thing to note is that when using the regression line to estimate values, if it's within the range given, it is called interpolation. If it's outside of the range it is called extrapolation and is less reliable. Questions may ask you to comment on the reliability and you answer with either one of these for one mark.

Do you get the forumlas for B = and A = or should I memorize it?

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#12

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oh can they? I have a Casio fx-83gt plus will do some research on that haha, ty

**Coerce**)oh can they? I have a Casio fx-83gt plus will do some research on that haha, ty

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#13

(Original post by

Yeah thats the same concept as it was with correlation.. I just got confused with the whole Regression line cause I seen some graphs where someone predicted it and started talking about regression.

Do you get the forumlas for B = and A = or should I memorize it?

**Coerce**)Yeah thats the same concept as it was with correlation.. I just got confused with the whole Regression line cause I seen some graphs where someone predicted it and started talking about regression.

Do you get the forumlas for B = and A = or should I memorize it?

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(Original post by

May depend on your board, but for AQA you get similar equations that if you modify slightly you get the formulae you need.

**morgan8002**)May depend on your board, but for AQA you get similar equations that if you modify slightly you get the formulae you need.

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#15

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Its not an actual paper.. just a mock on correlation and regression tommorow.. and how should i leave my last answer y = a+bx?

**Coerce**)Its not an actual paper.. just a mock on correlation and regression tommorow.. and how should i leave my last answer y = a+bx?

then when you've found b, b= such and such

Then write y = a + bx, with the numbers instead of a and b

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#16

**Coerce**)

Its not an actual paper.. just a mock on correlation and regression tommorow.. and how should i leave my last answer y = a+bx?

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(Original post by

Also for statistics you will probably get a formula booklet in a mock(you need a formula booklet)

**morgan8002**)Also for statistics you will probably get a formula booklet in a mock(you need a formula booklet)

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