Data Transformation

[haygirl]

I don't get how to work out what one to use.. so i have the circle of transformations but within each section there are a few different ones to use... How do i work out what one to use without putting it all into my calc? Sometimes not given enough info to be able to put it into the calc at times...

Thanks

[TyErd]

there all fine but if you were to choose one, you have to find out the transformation that gets you the highest correlation coefficient.

[haygirl]

Say its a multi choice question and a few of them are options... how do i know?

[TyErd]

if it asked which transformations were possible, then only one of those possible transformation will be an option, not all of them.  If it asked whats the most appropriate transformation, then you would have to find the correlation coefficient for each transformation, the highest one is the most appropriate.

[onerealsmartass]

usually they would provide you with some information and sometimes a graph.
Compare the graph to the ptoential transformation graphs.
Whichever graph appears to be the most similar use that transformation, but sometimes there may be a better transformation - look at the correlation coefficient like TyErd said

[_avO]

Earlier today I was doing an old Kilbaha exam there was one of those Multiple choice questions with transformations, and 3 of the 5 options were applicable however there were no values given so I had to guess (got it wrong).. This better not happen in the actual exam

[onerealsmartass]

yeah that would suck.. but i dont think vcaa will do that, it has to be fairly straightforward and simple

[haygirl]

I was doing a VCAA one and it had a graph and then had the options but there was more than one of the options that would fit.. but not enough info was giving to be able to put it into my calc to work it out... so yeah

[_avO]

If I may, which exam were you doing? I wanna check it out

[TyErd]

yeah same

[haygirl]

2009

The core question 12

[_avO]

All you need to do is roughly estimate each point on the graph, plot it in your calculator, produce a transformation and determine the highest r value. Yes it may take some time but the previous questions are most likely quick and easy

EDIT: After looking at that question closely, there is only one answer possible which is C. Correct me if i'm wrong

[haygirl]

C is correct....

So u think the best way to go about is it so put it roughly into the calc and go from there?

[_avO]

No if you read it, it says mathematics against internet usage. This represents y vs x
The transformations possible for this graph are:

y^2 vs x
y vs log(x)
y vs 1/x

Now if you refer back to the possible answers, only C (mathematics against log(internet usage)) applies so therefore thats the only answer, no calculations necessary

[haygirl]

Thanks i can see it now....