Use the correlation coefficient to find the coefficient of determination. What percent of variation in the response variable can be explained by changes in the explanatory variable?
r = -0.5

Question

Use the correlation coefficient to find the coefficient of determination. What percent of variation in the response variable can be explained by changes in the explanatory variable? 
r = -0.5

daniellelovee · Answer

coefficient of determination: 0.1; 10% of the variation in the response variable can be explained by changes in the explanatory variable. 

coefficient of determination: 0.25; 25% of the variation in the response variable can be explained by changes in the explanatory variable. 

coefficient of determination: 0.5; 50% of the variation in the response variable can be explained by changes in the explanatory variable. 

coefficient of determination: 0.71; 71% of the variation in the response variable can be explained by changes in the explanatory variable.

daniellelovee · Answer

@AlexandervonHumboldt2

daniellelovee · Answer

@tkhunny

tkhunny · Answer

What do your course materials say?

tkhunny · Answer

Don't make me read it.  I already know what it says.  What are the salient points?

tkhunny · Answer

Which is the Coeffi8cient of Variation?  r, r^2, or something else?

daniellelovee · Answer

idk im sorry I have no idea whatsoever how to solve this thats why I would like your help

tkhunny · Answer

The REAL help is you learning how to learn. Sometimes it takes searching.  Sometimes it takes explanations.  Sometimes it takes examples.  I like to vary it.

daniellelovee · Answer

can you explain? or do what you think best please I really want and need to learn it

tkhunny · Answer

If the Coefficient of Determination explains a percentage of the variation, it can't very well be negative.  Thus, it must be r^2, not r.

daniellelovee · Answer

so -0.5^2?

daniellelovee · Answer

1/4

daniellelovee · Answer

?

tkhunny · Answer

Careful with notation.

-0.5^2 might mean -(0.5^2) = -0.25

(-0.5)^2 = 0.25 and cannot be mistaken for the negative value.

daniellelovee · Answer

yeah I was wondering that but I thought it was the first one

tkhunny · Answer

In some computer languages, 

-0.5^2 = (-0.5)^2 = 0.25

In others, it is as shown above.  You have to know or you will not get your mars lander in the right orbit.  :-)

tkhunny · Answer

Adding parentheses for clarification is almost never a mistake.

daniellelovee · Answer

yeah I learned that some time ago lol but was the positive answer the correct one or not?

daniellelovee · Answer

@satellite73

tkhunny · Answer

Review: If the Coefficient of Determination explains a percentage of the variation, it can't very well be negative. Thus, it must be r^2, not r.

r^2 cannot be negative.

daniellelovee · Answer

ohh ok got it therefore my first answer was correct, im ready for the next step :)

tkhunny · Answer

In 5-8, you are given r.  -1 <= r <= +1 and 0 <= r^2 <= 1

tkhunny · Answer

Yea!!

daniellelovee · Answer

alright does that mean tha B is the correct choice?

tkhunny · Answer

I don't see a "B".   I see only numbered problems.

daniellelovee · Answer

coefficient of determination: 0.25; 25% of the variation in the response variable can be explained by changes in the explanatory variable.

daniellelovee · Answer

is that it?

tkhunny · Answer

Wow!  I forgot the problem started all the way up there.  Yes!!

daniellelovee · Answer

alright thank you for you help :) and for teaching me