Internal reporting systems:

All enterprises which have been in operation for any period of time nave a wealth of information. However, this information often remains under-utilised because it is compartmentalised, either in the form of an individual entrepreneur or in the functional departments of larger businesses. That is, information is usually categorised according to its nature so that there are, for example, financial, production, manpower, marketing, stockholding and logistical data. Often the entrepreneur, or various personnel working in the functional departments holding these pieces of data, do not see how it could help decision makers in other functional areas. Similarly, decision makers can fail to appreciate how information from other functional areas might help them and therefore do not request it.
The internal records that are of immediate value to marketing decisions are: orders received, stockholdings and sales invoices. These are but a few of the internal records that can be used by marketing managers, but even this small set of records is capable of generating a great deal of information. Below, is a list of some of the information that can be derived from sales invoices.

• Product type, size and pack type by territory
• Product type, size and pack type by type of account
• Product type, size and pack type by industry
• Product type, size and pack type by customer
• Average value and/or volume of sale by territory
• Average value and/or volume of sale by type of account
• Average value and/or volume of sale by industry
• Average value and/or volume of sale by sales person


Reference:
http://www.fao.org/docrep/w3241e/w3241e0a.htm