Best Fit in Excel

Hello All:

I am trying to compare an observed dataset with three best-fit models

I wish to see which candidate model best fits the observed dataset.

Is there any way to do this in Excel? I know there is a correlation of determination available, but I only know how to compare observed data with a best-fit model Excel creates.

Thank you!!

Jo

PS: The datasets are not the same size (i.e. observed x=50 points, y=50 points. models x=1030 points, y=1030 points)