Programmed edit checks are edits automatically performed by data entry programs upon entry of the input data. Erroneous data may be highlighted on the terminal screen to allow the operator to take corrective action immediately. Programmed edits can highlight actual or potential input errors, and allows them to be corrected quickly and efficiently. The most common types of programmed edit checks are the following:

1. Reasonableness checks. Reasonableness checks, also known as limit checks, test whether the contents (e.g., values) of the data entered fall within predetermined limits. The limits may describe a standard range (e.g., customer numbers must be between 0001 and 5000, months must be 01 to 12), or maximum values (e.g., no normal hours worked greater than 40 and no overtime hours greater than 20).
2. Document/record hash totals. Document/record hash totals are a summary of any numeric data field within the input document or record, such as item numbers or quantities on a customer order. The totaling of these numbers typically serves no purpose other than as a control. Calculated before and then again after entry of the document or record, this total can be used to determine that the applicable fields were all entered and were entered correctly.
3. Mathematical accuracy checks. This edit compares calculations performed manually to those performed by the computer to determine if a document has been entered correctly. For this check, the user might enter the individual items (e.g., quantity purchased, unit cost, tax, shipping cost) on a document, such as an invoice, and the total for that document. Then, the computer adds up the individual items and compares that total to the one input by the user. If they don’t agree, something has likely been entered erroneously. Alternatively, the user can review the computer calculations and compare them to totals prepared before input.
4. Check digit verification. In many processes, an extra digit—a check digit—is included in the identification number of entities such as customers and vendors. More than likely you have a check digit as part of the ID on your ATM card. The check digit is calculated originally by applying a complicated and secret formula to an identification number; the check digit then is appended to the identification number. For instance, digit 6 might be appended to customer code 123 so that the entire ID becomes 1236. In this highly oversimplified example, the digit 6 was derived by adding together the digits 1, 2, and 3. Whenever the identification number is entered later by a data entry person, the computer program applies the mathematical formula to verify the check digit. In our illustration, if the ID were input as 1246, the entry would be rejected because the digits 1, 2, and 4 do not add up to 6. You are already saying to yourself, “But what about a transposition like 1326?” 
5. This entry would be accepted because of the simple method of calculating the check digit. In practice, check digits are assigned by using much more sophisticated formulas than simple cross-addiction; those formulas are designed to detect a variety of input errors, including transpositions.

Review Question

What are two common programmed edit checks? Describe each check.