A reasonable expense is justified to find out where replies do come from, for it is as much to the advertiser's interest to continue the use of all profitable mediums as to drop the unprofitable ones. Many of the most successful advertisers, however, consider it safe to distribute unidentified replies pro rata, basing the distribution on the number of keyed replies--that is, if 30 per cent of all keyed replies can be traced to the Technical World, that magazine will be credited with 30 per cent of all unidentified replies. When the mail is opened all replies should be sorted by key numbers, inquiries and orders separated. Then the total number of inquiries, and number and amount of orders from each publication should be ascertained and credited. For recording credits a form, similar to the one shown in Fig. 15, should be used. This may be on a card or in loose leaf. A card is used for each ad, in each publication--that is, if there are seven insertions in the Technical World in one year, seven record cards will be used--one for each insertion. These cards or sheets are to be filed under the names of the publications. On the back of the card the form shown in Fig. 16, is printed. This provides for a daily record of sales resulting from the inquiries recorded on the face, or from the ad if it calls for direct orders. These forms supply all necessary data for a complete statistical record for each publication. Too much time would be required to look through all of these cards every time information is desired about a given publication; a more condensed record of total results should be provided. [Illustration: Fig. 17. Combined Record of Insertions, Costs, and Sales] All of the information of practical value can be combined with a record of insertions on the form shown in Fig. 17, using a sheet for each publication. The record includes the date of order, space, subject, copy No., cut No., dates of insertion, checking, and proofreading, the date and amount of bill, and the number, amount, and average cost of sales. The record of sales should be entered monthly from the detail record. [Illustration: Fig. 18. Daily Record of Sales of Advertised Goods in a Retail Store] These sheets are filed in a loose-leaf binder, indexed alphabetically under the names of the publications. One sheet will accommodate the full yearly schedule for a monthly or weekly publication. _Retail Advertising Returns._ To check returns from retail advertising is quite a different problem from checking returns from keyed ads in monthly magazines. There are no keys, and no mail inquiries to be traced. But a record of general results is very desirable, and it is possible to obtain records which will, at least, indicate the increase in sales due to advertising.