Question

TEST TOMORROW PLEASE HELP

In linear regression, is r the correlation coefficient, or r^2 the correlation coefficient?

Also, how would you describe how strong or weak the correlation is? For example, if the correlation was -0.97, would the correlation be a strong negative or positive correlation? Do you need the negative or positive in there?

Answer 1

r is the correlation coefficient

r^2 is the coefficient of determination

Answer 2

if r is close to either +1 or -1, then it has strong linear correlation

if r is close to 0, then it has weak or no linear correlation

Answer 3

if r is positive, then it has positive correlation

if r is close to +1, then it has positive linear correlation

same applies for -1 (just replace positive with negative)

Answer 4

So if r is -0.97, the it would be a strong linear negative correlation?

I also had one more question, do you mind helping me out with that one as well?

Answer 5

yes correct and go ahead

Answer 6

I have this tabel:
Wind Speed: 0, 6, 9, 12, 17, 20, 22
Temp.: 32, 28, 22, 18, 16, 10, 3

I need to find what the temp. if the wind speed is 30. How would I do that?

Answer 7

sounds like you need to find the equation of the linear regression line

Answer 8

do you know how to do that?

Answer 9

The equation is y=33.5-1.2x

Answer 10

ok let me check

Answer 11

Alright

Answer 12

I'm getting y = -1.23x + 33.56, so that's pretty close to what you have

Answer 13

now you plug in x = 30

Answer 14

Oops, I must have switched the numbers lol. Sorry. Ok, so I plug in 30 and I got -3.34.

Answer 15

me too

Answer 16

So that would be the answer right?

Answer 17

yes it would, it is an approximation/estimation though

Answer 18

because the regression line isn't perfect

Answer 19

Wait hold on.

Answer 20

When I go to the LinReg screen or whatever, the equation y=a+bx shows up, and a is equal to 33.56 and b is equal to .94. So wouldn't I be right then? I mean, wouldn't you have switched them around then?

Answer 21

make sure you have your data typed in correctly

Answer 22

the slope should be negative

Answer 23

Idk what I'm doing wrong.

Answer 24

your x data is in L1 right?

Answer 25

X meaning wind speed right?

Answer 26

yes correct

Answer 27

that is L1

Answer 28

L2 is the temp

Answer 29

That's what I did.

Answer 30

you should have this for L1 and L2

Answer 31

I do have that lol.

Answer 32

Maybe try reading your equation and all that again?

Answer 33

I'm getting this when i do LinReg

Answer 34

Hmmmmmm.
I wonder what's happening.

Answer 35

which matches up with what geogebra is saying, which is

y = -1.23x + 33.56

Answer 36

Ok so then something is probs wrong with my work.

Answer 37

btw, a+bx and b+ax are just two different versions of the same thing really

Answer 38

Wait so did I get the right equation then? And btw, when you got to the LinReg(ax+b) screen, did you go down to calculate and hit enter and then get your information?

Answer 39

yes that's how I got that screen

Answer 40

and no, your equation is off

Answer 41

33.56 is correct

but the 0.94 is wrong

Answer 42

Jim need your help

Answer 43

ok one sec

Answer 44

I hit calculate and I'm still getting the same thing :(

WAIT! Lol.

The first equation I got was y=33.5-1.2x. That's the same as y = -1.23x + 33.56, well close to it anyways. I think. Yeah it was the same thing right?

Answer 45

yeah pretty close

Answer 46

so it's rounding somehow, but it looks right now

Answer 47

Okay :) Thank you so much! I appreciate your time and help :)

Answer 48

you're welcome