I am trying to fit lactation curves for different breeds of dairy cattle using Wood's curve with an adjustment for season (s). The model is: y(t) = s a t^b e^-c*t My current code is: parms a=3 b=0.25 c=-0.0016; model milk=season*(a*time**(b)*exp(-c*time); by breed; output out=pred1 p=predict r=residuals; run; Code for plotting predicted values: proc gplot data=pred1; plot predict*time=breed; run; quit; However when I plot the predicted production values for separate curves for each breed the graph instead plots all 3 breeds by season. How do I get this corrected so I get the graphs for just the breeds and not every season? Here's the graph I'm getting and an example of the graph I am trying to get: this is the graph I am getting that is not right Here's an example of the graph I want Thank you
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