Using SET VARIABLE PARAM_EFFECTIVE_DATE

Summary

I'm trying to default the "SET VARIABLE PARAM_EFFECTIVE_DATE=" back 3 days

Content

I'm trying to set the "SET VARIABLE PARAM_EFFECTIVE_DATE=" prefix.  I want to use the current date minus 3 days.

I've tried something like this but it's not working.  The "TIMESTAMPADD(SQL_TSI_DAY, -3,CURRENT_DATE" gives me today minus 3 days in the report.  But I don't have the correct syntax.

I've tried...

SET VARIABLE PARAM_EFFECTIVE_DATE='@{TIMESTAMPADD(SQL_TSI_DAY, -3,CURRENT_DATE}';

Anyone know what I'm missing?

Thanks!