Should UTC timestamps, such as those in Stack Exchange hover-texts, include day of the week?

Question

There is a proposal on Meta Stack Exchange to add the day of the week to the hover-texts for timestamps on Stack Exchange, which currently show a raw UTC timestamp, of the form YYYY-MM-DD HH:MM:SSZ, where the 'Z' is a literal that indicates that it is a UTC timestamp.

^{screenshot used in the MSE proposal, by rolfl}

The context, of course, is an online event in a system used around the world. The timestamps are used by various people for various purposes. Some uses, as highlighted in the MSE proposal, require determining the local day of the week associated with the timestamp.

There was discussion in the comments about whether prepending the day of the week, yielding, e.g., Mon 2015-01-26 09:22:17Z, would be, on balance more helpful or more harmful.

• Helpful: Allows the viewer to see, at a glance, what day of the week (UTC) the event occurred on. The viewer can translate from UTC to another relevant time zone and, in the process, determine whether to adjust the day of the week along with the hour and date.

• Harmful: Makes it more likely that a viewer interested in the day of the week will miss the fact that it's a UTC timestamp and will take the shown day of the week as valid.

In such a context, should UTC timestamps include day of the week or not?

Is there UX literature, or are there standard UX design principles that address this question?

Answer 1

Timestamps aren't meant for most users

Showing friendly names such as 2 hours ago or yesterday can quickly provide context to the user as opposed to showing them 2015-01-27 18:54:03.259 Mixing both formats together will always cause friction (anything that forces a user to ask a question in their mind adds to cognitive friction). In almost all cases mixing them will do more harm than good so leave off the day of week. Even at the expense of providing context, there should be no question that what I'm looking at is a timestamp.

While friendly date formats are better displayed in the UI by default, timestamps should be hidden until a user requests it (such as hovering the mouse over a displayed date/time or changing a setting)

Friendly names such as the ones used in Outlook provide better context than Monday or Friday. The names for each day of the week loses context every 7 days. Saying Tuesday today might help a little but saying Tuesday next week would be confusing even without bringing timestamp in to the mix...

Answer 2

Displaying the day of the week (e.g. Monday, Tuesday) usually only makes sense when the date is either recently passed (i.e. within the last week) or in the future. When a date has recently passed, stating the day of the week makes it easier to recognise within that limited context. For future events, knowing on what day of the week it's due to take place is more useful than having to consult a separate calendar.

For something that happened several weeks, months or years ago, there is little value in explicitly stating the day. I think that holds true with questions on Stack Exchange. I don't see any real value in adding that extra information and I can see some opportunity for it to cause confusion with timezones.

Answer 3

The Question's Title (repeated in the body too) is :

Should UTC timestamps include day of the week or not?

The answer is "it depends":

1. If humans don't need to know the Day-of-Week for a timestamp, then No.
2. If humans do need to know the day-of-week for the timestamp, but they can have the date processed for them order to determine the day-of-week, then no, the base timestamp does not need it.
3. If humans do need to know the day-of-week for the timestamp, and the process for computing that information would be manual, or time-consuming, then having it embedded in the timestamp would provide a much better user experience.
4. If no humans are involved, there's no need to include the Day-Of-Week.

That's the basic answer to the core question.

The question divides the components of the feedback in to 'helpful' and 'harmful':

• helpful: Allows the viewer to see, at a glance, what day of the week (UTC) the event occurred on

  That's the whole idea. The user needs to know the day, so telling them at a glance is surely helpful.

• harmful: Makes it more likely that a viewer interested in the day of the week will miss the fact that it's a UTC timestamp and will take the shown day of the week as valid

  That's a bigger UX item than the focus the day-of-week only. There's already confusion about the UTC timestamps, and users who 'hover' over those timestamps are mostly (all?) already familiar with the fact that it is in UTC. Adding the Day-of-week will not make those users any more confused. It is not the DayOfWeek that makes the timezone confusing, but the UTC itself. Additionally there are other reasons why UTC is/was chosen, and those reasons are beyond the scope of this question/answer.

  Bottom line, no, adding the day-of-week will not make it any more confusing than it already is. Many people miss that the timestamps are UTC already, and that's a different UX problem.

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Applying that logic to the example provided in the meta.se question:

• there's a timestamp
• there's a human element
• there's a need to know the day-of-week for the timestamp
• the system does not allow an easy, or automatic ability to present the Day-Of-Week for the date.

For the situation described in the meta question, the right answer would be to include the Day-of-week in the timestamp.

An interesting User Experience question would be where in the timestamp, but that is not what this UX question asks.

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The tail of the question is:

Is there UX literature that addresses this question, or are there standard UX design principles that do?

The basic question is: A user needs to know the Day Of Week for a date, the US Government has a website tailored for Usability: www.usability.gov and it has the following key components for usability:

image in public domain, but credited to Peter Morville

Where the 'Usable' aspect is defined as "Site must be easy to use", and the 'Findable' aspect is defined as "Content needs to be navigable and locatable onsite and offsite"

Making the required information (day of week for a date) only available 'off-site' is clearly a violation of the Usability and Findability aspects.

Answer 4

Based on your question being centered around the MSE proposal:

I would say the answer would be no!

I don't think it'd be helpful at all due to users reading LTR would see the day and time and totally stop reading and miss the Z realizing it was a UTC date/time.

I would instead suggest that it would be helpful in the context where you actually provide the user a tooltip that displays the Day, Date, and Time as it pertains to their UTC offset (if any), or their current culture.

This answer from Matt Johnson seems to be a step in the right direction.

Answer 5

I think a solution is.

Don’t change the hover text. But add the day in local time to the “asked 2 days ago” texted. So show “asked 2 days ago (Web)” or “asked Mon Mar 6 '13 at 12:24” I don’t need to know if day if it is less than 24 yours ago, or yesterday.