Curve fitting a) define intersect b) fit without pre-defined fittype

Hey guys

I have some data (let's say X and Y) and I think it fits probably best to a 'power1' fittype. I have used the curve fitting toolbox as well as fitted programmatically of which I prefer the latter (because I have many datasets and I don't particularly like clicking buttons).

Two questions:

a) I know my model has to go through (0,0) and through (1,1). How can I force it?

b) Even though I think it'll be something like y= c*A^z, I would like something like "free fitting" where just the bulk of data is taken into account and fitted. I would like to avoid giving a fittype. Is this possible?

Answer 1

[Jacob Mevorach]

If I was going to do this I would try a variety of fits for each I thought might be good and I'd calculate the r^2 value for each and then go with the fit which had the maximum r^2 value.

[Laura Iten]

I did that. But I wanted to go beyond defining a fittype already. Also, I would've liked to know which points would be considered as outliers under the "free fit" conditions.

Do you happen to have an idea how to solve a)? Fit through 0,0 and 1,1 ?