By default, the user specified (user property) for a configured connection (<connection> XML element in dashboard configuration file) is used to calculate filter and measure values for a query. This user's process and data access privileges apply to the Performance Dashboard. This means that a dashboard user may be able to see data for which he or she does not have access privileges in PPM.
If you want to use login-specific data access dimensions in your Performance Dashboard, you must specify the value <by_login_user for the <data_retrieval attribute in the <connection> XML element for the corresponding connection. In this case, filter and measure values are determined using the ID of the logged in dashboard user.