Reproducing a smooth curve with random data

Hi guys,

I would like to reproduce the above figure with random data. How can I do it? We lost the source code to reproduce the RMSE so we need to reproduce it manually. The idea basically is to produce 10 curves (blue one and red ones) taht smoothly reproduce the picture above. Is it possible to do so?

Thank you

[darova]

What about spline?

[federico nutarelli]

Good idea. I was doing fit and smooth but sppline is better