Richard Methot

Brainstorming: set alpha = parm(3) and beta = parm(4) as leading, estimated parameters then R0 = parm(1) and steepness = parm (2) can be derived and reported per existing outputs...

got it working and produces same result as R0, h approach. implemented parameters as ln(alpha) and ln(beta) code calcs derived R0 and steepness and saves them to SRparm(1) and SRparm(2)...

attached is spreadsheet in which I investigate plausible ranges for the alpha and beta parameters. @timjmiller/wham Do you have any tips on parameterizing the alpha beta? [test_AB_range.xlsx](https://github.com/nmfs-stock-synthesis/stock-synthesis/files/10702389/test_AB_range.xlsx)

Thanks Ian. In my first trials, I can get the same answer (haven't done any trials with time-varying biology yet) as with the R0,h approach, but convergence path is ragged....

something got broken in MSY calcs

Thanks Tim. I got off-track for awhile until realizing that SS3 already had some alpha, beta code based on R = aS/(b+S) such that your a,b and mine did not...

We need careful consideration of implications for depletion calculations. They already are somewhat wrong when there is time-varying growth.

R0h and AB are looking identical except when R0 parameter is time-varying. Basically R0h and AB both define parameters that are relevant to virgin (year 1) biology, then implement the...

Tim, The SS3 implementation of the R0h approach does not update the unfished SSB/R when there is time-varying biology (except in the rare case where there is a regime shift...

Let me work out the examples before responding further. R0 and the R0,h approach are very deep in the DNA of SS3. Major changes to SS3 are not anticipated; instead...