Appropriateness of 24 hour clock

Posted: Sun Jun 15, 2008 6:05 pm Post subject: Appropriateness of 24 hour clock

I'm currently going through the process of evaluating the suitability of using the 24 hour clock to elicit time input on web forms from people. OK,you say, like any presentation it depends on the audience. OK, I say, there is a thought process behind the evaluation against the audience, so what are the criteria?

Say there are two ways of getting input, 1. a box where you type "13:45" or 2. a box for 1:45 and a dropdown list that contains AM or PM. There are arguments for and against both approaches.

1 is good since it is only one box and therefore only one place to make a mistake.
1 is bad since some people take their brain out of gear when using the 24 hour clock, putting in 16:45 for 6:45 pm.
2 is good since the hour can be correct
2 is bad since if the brain is out of gear then they select am or forget to change to pm.

Anybody been through this process? How do people feel about using the 24 hour clock, and is there any hard reason to prefer one over the other?

Posted: Mon Jun 16, 2008 6:18 am Post subject:

Interesting question which I've never given much thought to...

On a quick early morning mental review I am unable to remember any web forms I have filled in recently which contain a time field. However we have a number of devices round the house incorporating digital clocks which require resetting after a power failure. All of these, bar one, use a twenty four hour clock with the exception - the answering machine that needs a pm/am input - being far and away the one I find most tedious.

Not exactly a statistically valid sample, but an indicator perhaps?

Regards,

Pete

Posted: Mon Jun 16, 2008 9:26 am Post subject:

My vote - 24 hour clock.

(12am = midnight, 12pm = midday but many people get this wrong)

NetHosted Customer Joined: 05 May 2005 Posts: 147

For what it's worth, ISO 8601 uses the 24-hour clock system:

http://en.wikipedia.org/wiki/ISO_8601

Posted: Mon Jun 16, 2008 6:58 pm Post subject:

Having done a bit more 'background processing' on this over the course of the day, I have come to the conclusion that, unless there were very good reason not to, I would implement this with two simple drop downs - one for the (24) hours the other for the minutes.

Reasoning being; I believe that people nowadays are generally comfortable with the twenty four hour clock, it reduces the number of form fields to the minimum practicable and it also simplifies the data input filtering/validation.

Just my thoughts.

Pete

Posted: Sun Jun 29, 2008 8:50 pm Post subject: