Three output formats for maxent

[Linna zhang]

Hi there,

Could anyone tell me the differences between three output formats for maxent, 

namely raw, logistic and cumulative? How to interpret these three output formats

when making analysis? We usually use logistic output, but under which condition

can we use other two formats?

Another question is that what's the lowest presence threshold (LPT)? Where can 

I find the LPT value? How to select the specific value of the LPT?

Thank you in advance. 

Linna

[John Clark]

From the Maxent help file:

raw: output values are probabilities (0 - 1), the sum of all cells used during training is 1.  Therefore, most of your values will likely be very small

logistic: also probabilities (0-1), but scaled up in a non-linear way for easier interpretation.  If the probability of presence is ~ 0.5, log output can be interpreted as the probability of occurrence at that location.

sum: value of a grid cell is the sum of the probabilities of all cell with no higher probability than the focal cell, times 100.  Best conditions at 100, unsuitable near 0.

Logistic is probably your best option, but some evaluation methods (AICc from ENMtools) require raw output.

As far as LPT, it sounds like you're talking about thresholds for reclassifying results into binary suitable/unsuitable coverages.   Several different thresholds are provided with the Maxent html output (perhaps you mean minimum training presence?) that provide the values (cumulative or logistic) used to reclassify outputs in a GIS.  Note these are not provided within the summary for replicated maxent models, only the individual runs.  Hope that helps.

Best Regards,

John Clark

Linna

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[张琳娜]

Hi John,
It's very helpful for me. Thanks a lot!