Thread: Basic correlation question

I'm tossing up between a. and e. and I don't have the answers, what do you guys think is the correct choice?

Thanks

This is the question:

http://img4.imageshack.us/f/asdfyn.jpg/

I can't read the text in the image

CB

A scientist has found that there is a correlation of r = -0.39 between eye colour (black, green, brown) of guinea pigs and the amount of alcohol that is fatal to the animal when consumed. This indicates:
a. nicotine is less harmful to one eye colour than the others.
b. one must always consider the eye colour of animals in making statements about the effect of nicotine consumption.
c. the researcher needs to do further study to explain the causes of this negative correlation.
d. the researcher needs to take a course in statistics because correlation is not an appropriate measure of categorical variables.
e. the lethal dose of nicotine goes down as the eye colour of the animal changes.

Here it is.

But I'm surprised that the question is implying that alcohol contains nicotine... ethanol is present in alcohol and nicotine is found in tobacco.

But I would say d. I haven't studied linear regression, but I don't think that colours can be put on an axis and a certain relationship put. I would have accepted if they put the wavelength or frequency of the colour, but not discrete colours.

Originally Posted by usagi_killer

I'm tossing up between a. and e. and I don't have the answers, what do you guys think is the correct choice?

Thanks

This is the question:

Imageshack - asdfyn.jpg

1. the correlation is small

2. As there is no inherent ordering of eye colour the correlation is meaningless (choose three random number ~U(0,1) sort them into descending order and compute the correlation, also consider the distribution of the correlation between the three numbers unsorted)

3.The text metions alchol the answers nicotine, maybe typos?

4. d, seems OK but for incomplete reasons

CB

Originally Posted by CaptainBlack

1. the correlation is small

2. As there is no inherent ordering of eye colour the correlation is meaningless (choose three random number ~U(0,1) sort them into descending order and compute the correlation, also consider the distribution of the correlation between the three numbers unsorted)

The SD of r^2 for three random numbers sampled from U(0,1) is ~=0.7, so even if this were a valid process it would be of no significance.

CB