My dataset is attached (it's just a comma-delimited .txt file - change the extension to ".csv" to open in Excel). In the dataset, I have the following values:

- dfn
- h
- p
- s
- ul

I need to form an equation that best fits my data and solves for "ul" (ul=?). This will not be a linear equation. I have ran linear regression on the dataset in Excel but the margin of error(?) was too large. I'm no Math wiz, I took several Calculus classes in college, but that was 15 years ago and I rarely use it.

I understand that in order to do multivariate non-linear regression on my data, I need to come up with a model equation. This is where my head explodes, I have no idea what this model would look like. Can someone maybe tell me what the model equation should be or at least point me in the right direction to determine it? Again, I don't speak high level Math, so try to put it in English for me

data3.zip