Questions to ask yourself before you start
- Before you decide to design a reference number, ask if users really need one.
- Could the same be achieved with the user’s name or email address?
- If the user has a login, can they see their transaction status and history online?
The purpose of the reference
- Make it clear what the reference is for and what the user might do with it.
- If the user should write it down, tell them. But don’t rely on them doing this. Make sure the user receives the reference in any case (for example: in an email, text message, or accessible .pdf download).
- Only give the user one reference for a transaction. Users get confused sorting through different references.
Don’t rely on reference numbers
- Don’t force users to remember reference numbers to use your service.
- Reference numbers may be useful to quickly identify transactions, but have fallbacks in place (e.g. user’s name, email address, date of transaction, other transaction content).
Referring to reference numbers
- Give the reference number a simple, plain English name: e.g. application number, reference number.
- Don’t use internal system names or acronyms (for example: SIK number for System Identification Key number.)
Chunking and chunks
Definition: In general usage, a ‘chunk’ means a piece or part of something larger. In the field of cognitive psychology, a chunk is an organizational unit in memory.
An example of chunking could be a phone number if you compare +1-919-555-2743 to 19195552743 which one is easier to remember or to say out loud? We see this chunking approach in other areas such as debit cards for card numbers and sort codes.
UX-Definition: In the field of user-experience design, ‘chunking’ usually refers to breaking up content into small, distinct units of information (or ‘chunks’), as opposed to presenting an undifferentiated mess of atomic information items.
By chunking up a long number/letter string into a digestible format it can help your users and can improve their ability to comprehend and remember it.
Confusing numbers with letters
Another thing to think about is putting capital letters next to numbers can cause legibility issues in certain font families.See how similar O and 0 are in GDS Transport.You might want to consider a typeface optimised for numbers, or a monospace font which often have extra signifiers to identify similar characters; 0 and O. More can be found here: https://en.wikipedia.org/wiki/Alphanumeric
Year in the ID
To help customer services team adding contextual information can help call centre and admin staff (e.g. xxxx xx14 for transactions in 2014, and Axxx-xxxx for transactions relating to one service and Mxxxx-xxx for transactions for another service).
Service name at the start
To make it easier for the customer services team it would be best practice to have the prefix of the service at the start of the transaction ID e.g. report a discrepancy could be RD-00-00-00.
From the research it suggests that transaction ID’s should be chunked by either threes or fours. It allows the reader to use prosody (intonation to communicate that they’ve reached the end of the group/code), and It allows for a pause between each to allow the listener to repeat back or interrupt.
For ease of reading it would best practice to not mix the amounts of digits between each dash, for example, 000-00-00-000. Instead keep it consistent such as 00-00-00 or 000-000-000.
Where possible it would best to use numbers only after the service name ID. This will avoid confusion over the phone as someone could get confused between saying 0 and O (as mentioned above with confusing numbers with letters). Numbers are also easierread over phone.