Fitting Different Slopes Common Intercepts

[#1]

Hi - i am unsure how to fit a regression model with different slopes BUT a common Interecpt. 

Assume Y=response, GROUP (2-levels),  TIme (Covariate)

Kind regards, Vince

[#2]

on here appreciating this older tip about using Fit Model by not centering polynomials and just thought I'd note that in Fit Model the Expanded Estimates are a little less cryptic, especially if there were more groups.  I'll be using those where I want to get the slopes out of there with JSL but can see that the plot from Fit Y by X is nicer.

[#3]

Thansk...however when i adopt the below approach the graph of Y verus TIME by group - doesnt appear to haev a common intercept. Howevre if i change Time to an ordinal variable..seems to work OK.

[#4]

Here is another approach, using the Nonlinear platform.  Attached is an example:  you need to set parameters to be solved for, with a single intercept but varying slope parameters for the two groups.  The script is saved for the solution.

[#5]

thanks much appreciated.