On Wednesday, September 23, 2015 at 2:21:38 PM UTC-4, BottleMan wrote:
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.

Thanks for your help.

Ottmar

Thanks Claus, this worked. How did you get the formula? When I go to exponential trendline Excel comes up with: 2.7952e^0.0812x. Quite different from yours and only works for the lower numbers.

Ottmar