Density is Y axis, I'm need iterations with Gauss–Newton model if this is available. I have this example, but can I to use this or similar program with liner model or other models. proc nlin data=pplasma plots=fit; parms alpha=2 beta=0.4 gamma=0.00075; model conc = alpha/(gamma*(alpha-beta))*(exp(-beta*time)-exp(-alpha*time)); bootstrap / bootci; (I don't know why you don't accept those lines) output out=predictions predicted=prediction stdp=stdp lclm=lower95 uclm=upper95 residual=residual; run; proc print data=predictions; var conc velocity prediction stdp lower95 upper95 residual; run; Gauss–Newton
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