Help! Thanks!

Question

Help! Thanks!

anonymous · Answer

attachment

anonymous · Answer

@amistre64

amistre64 · Answer

this seems to ahve worked

anonymous · Answer

I guess. soooo... could you help out?

amistre64 · Answer

using the scatter plot tool .. where is your tool?

anonymous · Answer

I dont have one, and neither does the website, sooo i've just plotted it on an actual graph. :P

amistre64 · Answer

correlation coeff is a bugger to calculate by hand and my ti83 gave up the ghost a while back

amistre64 · Answer

you got excel?

anonymous · Answer

No. I only have word and powerpoint. :/

amistre64 · Answer

ive got mine loading, openoffice is a msoffice clone

anonymous · Answer

Oh okay. Was it easy to download?

anonymous · Answer

Is it still loading @amistre64

amistre64 · Answer

it was simple to download yes

but im used to excel commands, i cant find the corresponding commands in this one tho.  it has a scatter plot but i havent messed with it enough to know how to work it properly :)

amistre64 · Answer

we can work it by hand ... line of best fit, but then ill ahve to recall the pearson stuff

anonymous · Answer

Oh. Ok. If you can, i would like to work it by hand!

amistre64 · Answer

but i just found the help file :)

correl(a;b)

amistre64 · Answer

got it

we would need to define the slope of each best fit line:  x with respect to y, and y with respect to x

anonymous · Answer

Understood.

amistre64 · Answer

$$b=\frac{n\sum xy-\sum x\sum y}{n\sum xx-\sum x\sum x}$$
$$b'=\frac{n\sum xy-\sum x\sum y}{n\sum yy-\sum y\sum y}$$
$$r^2=bb'$$

anonymous · Answer

Ok, then?

amistre64 · Answer

well, r = sqrt(r^2)

anonymous · Answer

Hmm. ok.

anonymous · Answer

So, do I have to plug this formula for every problem?

amistre64 · Answer

if you insist on doing it by hand, sure.  otherwise use ... the .. scatter ... plot ... tool

n=8

    xx           x        y            yy          xy
460865   1909   1051   139529   253318

amistre64 · Answer

r = sqrt((8(253318)-1909(1051))^2/((8(460865)-1909^2)(8(139529)-1051^2)))

anonymous · Answer

hmmm. so the correlation is ......?

anonymous · Answer

correlation coefficient*

amistre64 · Answer

ive given you the process, and even filled in your values .. its up to you to simplify it

anonymous · Answer

ok.

anonymous · Answer

1.00?

anonymous · Answer

Is 1. correct? Thats what i seemed to get.

anonymous · Answer

@amistre64

amistre64 · Answer

http://www.wolframalpha.com/input/?i=sqrt%28%288%28253318%29-1909%281051%29%29%5E2%2F%28%288%28460865%29-1909%5E2%29%288%28139529%29-1051%5E2%29%29%29 not quite 1

anonymous · Answer

Oh. Okay. so 0.9 and the second answer is July. Thanks!

amistre64 · Answer

yep