Dear All,

I think it is good to include the SMAPE measure into the Rapid Miner regression performance operator.

http://en.wikipedia.org/wiki/SMAPEThis measure is more robust then correlation.

Allows to compare regression results from different data sets.

It is symmetrical. (Well not really, but better then MAPE)

Best regards,

Wessel

edit:

More detailed discussion:

http://www.buseco.monash.edu.au/ebs/pubs/wpapers/2005/wp13-05.pdfI'm not really sure what error measure is best.

But it is clear that a measure is needed which is somewhat independent on the data set.

Like a measure that ranges from 0 to 1. Instead of -infinity to +infinity.

second edit:

What constitutes a good error measure? First, a good error measure is clearly interpretable and summarizes the cost related to the error. Second, a good error measure is robust to outliers. Third, a good error measure is stable if only a few data points are used. Finally, a good error measure is unaffected by units of measurement.