Hi Ottmar,

Am Wed, 23 Sep 2015 11:21:33 -0700 (PDT) schrieb BottleMan:

I am doing a regression on real data to find the right formula. The data is as follows:
Wall Real time
2.2 3
2.4 3.3
2.6 3.6
2.8 3.9
3 4.2
3.2 4.5
3.4 4.9
3.6 5.35
3.8 5.8
4 6.35
4.2 6.8
Excel comes up with a formula: y= 0.0153x2+0.1931x+2.8388, The R2 is 0.9991. When I compute my data with the formula these are the resulting figures:
Calc. time
3.37494
3.43472
3.49634
3.5598
3.6251
3.69224
3.76122
3.83204
3.9047
3.9792
4.05554
Not at all like the real data. I tried other trendlines but none works. What am I doing wrong? I did this with some other data and it worked fine.

you get the exactest trendline with a XY chart. I got the formula
y=1,2416*e^0,4058*X
and with this formula the Calc time looks like this:
3,0318
3,2881
3,5661
3,8676
4,1946
4,5492
4,9339
5,3510
5,8034
6,2940
6,8262



Regards
Claus B.
--
Vista Ultimate / Windows7
Office 2007 Ultimate / 2010 Professional