on the SAS support, I've found the macro intracc which calculates the intraclass correlation coefficient.
In books, it is written that this value is between 0 and 1. However, with some data (where judges give very different marks) and using the macro, I've found negative values.
Is there an error in the macro ? Shall I changed these values to 0 ?
No, it doesn't matter if your data values are negative.
In general, there could be situations leading to negative estimates of ICC. It depends on how variance components used to calculate ICC are estimated. I am not familiar with this macro so I can only guess that the method of moments is applied.