Ask HN: Metrics to measure receivables and improvement in receivables

We at TimePay (timepay.co.in) are building products for enterprises in India to help them streamline their billing and receivables process and get paid by their clients on time. (Fulfilling jobs on credit and delayed payments is major problem for SMEs in India, often due to incomplete or insufficient communication) We are in search for a metric that we can track for our customers to signify changes in their receivables patterns, whether there is an improvement or not and is it due to our product or not. Existing standard metrics like DSO(Days Sales Outstanding) do not reflect the changes effectively. What other industry standard metrics are available? Has anybody here designed such a metric? If yes, what is it? If no, how do we go about designing such metric?