CPUE plot - Public Forums - Stock Synthesis

It seems to me that ss3 uses mean value, doesn't it?

Hello Yevhen,

Yes, this plot just uses the simple mean of the series to standardize each index and is created in the r4ss code rather than in SS directly.

Thank you for the reply.

How about such method

(Index-mean(Index))/sd(Index),

sd – standard deviation.

Might it be better for a wide variation case? But it seems to be "bad" when SD is close to zero.

Hi Yevhen,

To follow up on Ian's response, the place in the r4ss development branch code this standardization occurs: https://github.com/r4ss/r4ss/blob/development/R/SSplotIndices.R#L564

And most of the code for making this plot is also in the same function: https://github.com/r4ss/r4ss/blob/development/R/SSplotIndices.R#L779-L811

Thanks,

Kathryn

Dear Kathryn,

thank you for the links!

Hi Yevhen,

The initial intention of for this figure was to be able to identify consistent trends across indices on a single figure, hence the scaling around 1.0 .  This allows indices that have very different scales in relative abundance to be easily comparable.  The alternative calculation you suggested could be a useful additional figure for r4ss to include that could be complimentary to the current figure.  

Hi Yevhen,

Sorry, I missed your response about z-scoring indices instead of dividing by the mean to standardize. I can see why that would be useful. Is there any particular reason that plot would be more useful than the current one (or in addition to the current one)? r4ss welcomes contributions and it is always possible to add/change plots depending on the needs of the r4ss users.

Thanks,

Kathryn

I use z-scores for scaling in Cluster analysis. But the mean-centered method is "one-size-fits-all".
​​​​​​​Thank you for the explanation.