Introduction To Computing

1.5 Batch Processing

1.5.1 Batch Processing Steps

Particular care must be taken to ensure that all data is correctly transcribed and no documents are lost or entered more than once.

The following stages usually apply:

1. The source documents are scrutinised.
2. The documents are grouped into batches.
3. Every batch is given a header slip or cover note.
4. The number of each batch is written on its header slip and recorded in the batch register.
5. Control totals are calculated manually and written on the header slip.
6. The batch and its header slip are entered by data entry clerks into the system.
7. The source documents are verified (re-typed).
8. A variety of validation checks are carried out.
9. Any errors uncovered by the validation procedures are printed ona validation report and the errors will be corrected later.
10. Valid data is stored on disk or tape until it can be processed.

1.5.2 Validation Checks

Validation checks are performed to see if data has been entered correctly by seeing if it 'makes sense'.

Presence Check	Has data been entered?
Character Check	Is the input the correct length?
Picture Check	Does the input follow the correct pattern/format?
Range Check	Does the data fall within the correct range?
Check Digits	An extra number design to confirm the correct data has been entered.
File Lookup	Looks for entered data in a list or database file.
Control Totals	Do certain fields in all the records equal the manually inputted number?

1.5.3 Check Digits

Lengthy numbers such as a product can sometimes be entered incorrrectly.

A code number can be made self-checking by adding an extra digit that follows the code.

The Modulus 11 System

This is currently the most popular system. It catches about 99% of errors.

1	Each digit is assigned a weight.	1 5 8 7 × × × × 5 4 3 2
2	Each digit is multiplied by its weight. These numbers are then added up.	1 5 8 7 × × × × 5 4 3 2 = = = = 5 + 20 + 24 + 14 = 63
3	This number is divided by 11 and a remainder obtained.	63 ÷ 11 = 5 r 8
4	The remainder is subtracted from 11 to give a check digit.	11 - 8 = 3
5	However, there are two exceptions. If the this number is 10 then the check digit is zero. If this number is 11 the the check digit is X.	These exceptions do not apply to this number so the check digit is just 3 and the final code is: 1 5 8 7 3

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