It can be done by converting raw patient level data to log values in the data source by using a query. In tableau the arithmetic average of the log values will be the same as the geometric mean of the original values expressed in logs. Once the aggregations are finished you convert the log values back to normal values in Tableau.
1. Create new field (log_LOS) in the data source by taking the base 10 log of the LOS with the patient level data
2. Create a calculated field in Tableau for GMLOS, define as (10 ^ Avg(log_LOS))
Here is the example with log value calculations in Excel.
GMLOS.xlsx 10.7 KB