Days since the last logged two-way contact with a client, measured against the contact interval the client's tier requires. Silence on a top-tier client is the earliest signal of an outflow.
Quarterly for the top tier, twice a year for the middle, annually for the rest, or whatever the firm writes down. The measure needs the intervals to exist.
A list sorted by days overdue opens with the smallest client. Sorted by assets or revenue, it opens with the silence that costs the most.
Days since the last logged two-way contact, per client, divided by the contact interval the client's tier is owed. Above one is overdue.
A client owed quarterly contact was last spoken to 210 days ago: a ratio of 2.3. She holds $4 million with the firm and disclosed $6 million elsewhere at her last review.
Emails sent and newsletters counted as contact. The measure is a conversation, logged, with a date.