Calculation of Retention
At the beginning of each month, a snapshot of the data in the database is taken. Then a baseline date (ie. November 30, 2010) and a follow up date (ie. November 1, 2011) is selected which provides the data for November 2011. The report looks at all active staff as of the baseline date and checks how many of those staff are also active on the follow-up date. The number still active divided by the baseline number is the percentage of retention.
The retention rate will vary depending on what baseline date is chosen and on how long a time period there is between the baseline and the followup date.
Scroll over the lines on the graph to see additional information.