To evaluate the creditworthiness of customers, vendors, and suppliers, reach for the reference book used by bankers. Annual Statement Studies can tell how long you can expect collections to take, how much inventory a supplier is likely to have on hand, and typical profit margins for more than 345 industries.

Balance-sheet and income-statement data are presented for businesses with assets totaling up to $1 million, $1 million to $10 million, $10 million to $50 million, and more than $50 million. Also included are 16 ratios commonly derived from such information. Tom Bennett, executive vice-president of the Stillwater National Bank, in Tulsa, says the book is a handy way to judge your performance against your peers.

The book sells for $54.50, prepaid. Write Robert Morris Associates, 1650 Market Street, 23d Floor, Philadelphia PA 19103-9734.