Use Excel to find the similarity between functions.

[24forChromium]

I am writing a paper and I came up with a function that uses a hypothetical relationship to predict the value of one variable at different points in time, I graphed it, and then graphed the actual readings from an experiment. How can quantitatively describe how close the two trends are? In other words, how can I quantitatively describe the amount of support the hypothetical relationship get from the experiment? See image for more ideas, predictive function gives values in blue, actual readings are orange.

 

[DrClaude]

You could perform a χ² test. You can also calculate the R² for your model, since you already have the value for the linear regression.

If you don't know what any of that means, you can start with https://en.wikipedia.org/wiki/Goodness_of_fit

 

[FactChecker]

You can get the confidence intervals for the slope and intercept of the regression line. For a given confidence level, your theoretical parameters will be in or out of the confidence interval. Just eyeballing the data, the regression line, and your theoretical line, I think there is something missing from your theory. I think it is likely to be statistically rejected.