7. Methods of improving accuracy

Data validation

If the correct information to be exchanged conforms to a certain format, this fact can be used to filter out incorrect information. This is called data validation.

For example, a telephone number does not have alphabetic characters and so data validation can be used to spot erroneous data. This is commonly used with online forms.

Encoding

Two people trying to exchange a post code over the phone, are often frustrated because some letters sound almost the same - "Was that an 'M' or an 'N'? they might say.

In this case a code word is spoken instead of the actual letters.

For example, A,B,C becomes "Alpha", "Bravo", "Charlie".

The defence organisation NATO, realised it was critical that soldiers exchange information accurately and so they developed the NATO phonetic alphabet. Each letter has an agreed code word - E is Echo and so on. Now it is widely used by the police, emergency services or anyone who wants to improve accuracy over a phone or radio.

Encoding in effect increases the 'distance' between data items so it is easier to discriminate between them. Encoding works equally well with electronic data. Encoding is the principle behind error correction and detection. The disadvantage is that both ends of the exchange need to agree on the code words (i.e. protocol) and it takes extra bandwidth and time to transmit the codes.

Verification

The old comedy program 'Allo Allo' had a famous line "I will only say this once..." which always drew a laugh. In other words the listener had better pay attention or they might miss the message. This is an example of information exchange without verification. It is one-way communication.

A more robust way of exchanging information is for the message be be repeated back to the sender to confirm its accuracy.

When you pay by credit card over the phone, it is normal practice for the person taking the payment to speak back the number - "The number you provided is 119922229 , is that correct?" This is data verification and it works for both spoken and electronic information exchange. The disadvantage is that it takes extra time and bandwidth for the exchange.