st: RE: testing difference between maxima of 2 parabolas

 From "FEIVESON, ALAN H. (AL) (JSC-SK) (NASA)" <[email protected]> To "'[email protected]'" <[email protected]> Subject st: RE: testing difference between maxima of 2 parabolas Date Wed, 23 Apr 2003 08:55:00 -0500

```If you can append the data in such a way that both parabolas are estimated
in the same analysis, you can use -testnl-

Al Feiveson

-----Original Message-----
From: Julie Mao [mailto:[email protected]]
Sent: Monday, April 21, 2003 8:32 PM
To: [email protected]
Subject: st: testing difference between maxima of 2 parabolas

Does anyone know how to test whether the maximum values of 2 parabolas (for
which the coefficients for x and x^2 were estimated from a regression) are
statistically different?

Given that a parabola takes the form:

y = (A * x) + (B * x^2), where A and B are the estimated
coefficients,

and given that the maximum of a parabola falls at:

x = A/(-2*B) [from setting the first derivative = 0],

and that I have the SE's for A and B for both parabolas... is there a way to
test whether the maximum from one parabola differs from that of another
parabola?

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```