# [Ifeffit] Correlations

Scott Calvin scalvin at slc.edu
Mon Mar 1 15:00:16 CST 2004

```Thanks, Matt. That clarifies a few things...in particular, I found the
example you gave (quoted below) to be quite helpful.

--Scott Calvin
Sarah Lawrence College

At 12:16 PM 3/1/2004 -0600, you wrote:
>This is probably a bit off-topic from the original question (where
>I'd guess self-absorption to be the main issue,....), but let's
>consider typical fit results: S02= 0.9 +/- 0.1, sigma2= 0.015 +/-
>0.005, and a correlation between S02 and sigma2 C_S02_sigma2= +0.90.
>One could conclude from these that a true value of S02= 1.0 was
>reasonable.  But in order to get to S02= 1.0, sigma2 has to go up to
>~= 0.019 (~= sigma2_best + C_S02_sigma2 * delta_sigma2).  S02= 0.80
>is also reasonable, but this implies sigma2 would drop to around
>0.011.  The correlation means that, although having either S02= 0.80
>OR sigma2= 0.020 would be reasonable,t having both S02= 0.80 AND
>sigma2= 0.020 is much less likely.
>>
>--Matt
>
>

```