Re: can multicollinearity force a correlation?

> My tentative conclusion is that your 2% effect really > is a small one; it should be difficult to discern among > likely artifacts; and therefore, it is hardly worth mentioning I agree to me it makes sense as well: fasting insulin should have more to do with error and genetics than food

Re: can multicollinearity force a correlation?

On 18 Feb 2002 16:29:27 -0800, [EMAIL PROTECTED] (Wuzzy) wrote: > > You should take note that R^2 is *not* a very good measure > > of 'effect size.' > > Hi Rich, you asked to see my data, - I don't remember doing that - >i've posted the visu

Re: can multicollinearity force a correlation?

Wuzzy wrote: > > http://www.accessv.com/~joemende/insulin2.gif > > Appologies, i also forgot to divide the KCAL in food by the 31 as this > represents kcal. It seems to me logical to advise decreasing food > intake and increasing physical activity to improve insulin > sensitivity. I would prob

Re: can multicollinearity force a correlation?

> You should take note that R^2 is *not* a very good measure > of 'effect size.' Hi Rich, you asked to see my data, i've posted the visual at the following location http://www.accessv.com/~joemende/insulin2.gif note that the r^2 is low despite the fact that it agrees with common sense: Insuli

Re: can multicollinearity force a correlation?

http://www.accessv.com/~joemende/insulin2.gif Appologies, i also forgot to divide the KCAL in food by the 31 as this represents kcal. It seems to me logical to advise decreasing food intake and increasing physical activity to improve insulin sensitivity. I would probably avoid reporting the R^2

Re: can multicollinearity force a correlation?

[ snip, previous problem] > > This is similar to a problem I have come across: the measurement of a > serum value against exposure. > My theory is that they are correlated. But the data says that they > have an R^2 of 0.02 even though the p-value for the beta is p=1E-40 > (ie. zero). > > As y

Re: can multicollinearity force a correlation?

> low-fat vegan diet" would be close). However, the incidence of heterozygous > familal hypercholesterolemia is only 1:500,000, so this exposure contributes > little to the variance in serum cholesterol in the population; its r^2 would > be small. > > -Jay Thanks, This is similar to a problem

Re: can multicollinearity force a correlation?

Wuzzy <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > And that sounds impossible. I suspect a programming error. > > > > -Jay > > you're right i programmed a food database incorrectly but i've redone > it and yep the correlation was only 0.20 for kcal or so.

Re: can multicollinearity force a correlation?

"Jay Tanzman" <[EMAIL PROTECTED]> wrote in message news:... > Wuzzy <[EMAIL PROTECTED]> wrote in message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > It is because I am validating a 24hr dietary recall questionnaire > > using > > a food frequency questionnai

Re: can multicollinearity force a correlation?

> And that sounds impossible. I suspect a programming error. > > -Jay you're right i programmed a food database incorrectly but i've redone it and yep the correlation was only 0.20 for kcal or so. it is hard to program a database *into* another database easy to make errors.. i've made many err

Re: can multicollinearity force a correlation?

Wuzzy <[EMAIL PROTECTED]> wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > Hi Rich, okay i'll post the reason why I ask: > > It is because I am validating a 24hr dietary recall questionnaire > using > a food frequency questionnaire: It doesn't make sense to do that. > Amazingly I

Re: can multicollinearity force a correlation?

Hi Rich, okay i'll post the reason why I ask: It is because I am validating a 24hr dietary recall questionnaire using a food frequency questionnaire: as someone else pointed out i got an error, also a perfect correlation for pearsons. it is much more complicated than this but that is the scoo

Re: can multicollinearity force a correlation?

On 5 Feb 2002 18:01:15 -0800, [EMAIL PROTECTED] (Wuzzy) wrote: > > You made a model with the "exact same exposure in different units", > > which is something that no one would do, > > Hehe, translation is don't post messages until you've thought them > through. > > Anyway, turns out that the a

Re: can multicollinearity force a correlation?

In article <[EMAIL PROTECTED]>, Wuzzy <[EMAIL PROTECTED]> wrote: >Is it possible that multicollinearity can force a correlation that >does not exist? >I have a very large sample of n=5,000 >and have found that >disease= exposure + exposure + exposure + exposure R^2=0.45 >where all 4 exposures a

Re: can multicollinearity force a correlation?

I can't help it. the last paragraph in this post absolutely _demands_ a response. Wuzzy wrote: > > You made a model with the "exact same exposure in different units", > > which is something that no one would do, > > Hehe, translation is don't post messages until you've thought them > through. >

Re: can multicollinearity force a correlation?

To: [EMAIL PROTECTED] Date sent: 5 Feb 2002 18:15:00 -0800 From: [EMAIL PROTECTED] (Wuzzy) Organization: http://groups.google.com/ Subject:Re: can multicollinearity force a correlation? > In my own defense: > > I

Re: can multicollinearity force a correlation?

In my own defense: I was asking a simple question: will highly correlated cause an irregularly high R^2. My answer to my own question is "no" it can't.. No-one here was able to give me this answer and I believe it is correct: if your sample is large enough,(as mine is) then "no", multicolline

Re: can multicollinearity force a correlation?

> You made a model with the "exact same exposure in different units", > which is something that no one would do, Hehe, translation is don't post messages until you've thought them through. Anyway, turns out that the answer to my question is "No".. Multicollinearity cannot force a correlation.

Re: can multicollinearity force a correlation?

Would you please post the 5 * 5 R matrix? Wuzzy wrote: > Is it possible that multicollinearity can force a correlation that > does not exist? > > I have a very large sample of n=5,000 > and have found that > > disease= exposure + exposure + exposure + exposure R^2=0.45 > > where all 4 exposures

RE: can multicollinearity force a correlation?

Title: RE: can multicollinearity force a correlation? > Is it possible that multicollinearity can force a correlation that > does not exist? > > I have a very large sample of n=5,000 > and have found that > > disease= exposure + exposure + exposure + exposure R^2=

Re: can multicollinearity force a correlation?

On 5 Feb 2002 08:28:05 -0800, [EMAIL PROTECTED] (Wuzzy) wrote: > Is it possible that multicollinearity can force a correlation that > does not exist? > > I have a very large sample of n=5,000 > and have found that > > disease= exposure + exposure + exposure + exposure R^2=0.45 > > where all 4

Re: can multicollinearity force a correlation?

I'm curious to know why you're using the same exact exposure in different units. I've included a dichotomized version of a continuous exposure variable to look at potential threshold effects, but I've never heard of anyone doing what you've described. At 08:28 AM 2/5/02 -0800, Wuzzy wrote: >

can multicollinearity force a correlation?

Is it possible that multicollinearity can force a correlation that does not exist? I have a very large sample of n=5,000 and have found that disease= exposure + exposure + exposure + exposure R^2=0.45 where all 4 exposures are the exact same exposure in different units like ug/dL or mg/dL or m