To Number or Not To Number

Question

Here's a portion of a display from an iOS app that allows users to connect to a Wireless Valve Control device.

UPDATE: My question is regarding the -42 dBM and 2.97V labels.

As a code implementor, whether to show a number, an analog graphic, or both, has always been kind of "what seems to work best".

When space gets small, icon only is often nice. Icons only here might work, but the numbers add a bit of increased fidelity to the reading and help communicate what the icon is actually describing.

Is there a more rigorous/disciplined approach to when one should include the numeric value of a status value? Other than "that looks best/is nice to have"?

Answer 1

Probably the two key deciding factors for me would be (other than the physical space available to display the information, which affects readability):

• use case for the information
• level of accuracy required

You will find that if it is just something that allows the user to take a quick glance and perhaps to do something quickly, then the graphical representation is usually sufficient (e.g. do I need to recharge batter or not?). But if it is to get an idea of how long the battery will last for then instead of the amount of charge left in the battery you might even want the number of running time left (at current usage rate).

The level of accuracy relates to the use case, because a user might be required to enter in detailed information for a particular task and therefore the degree of accuracy becomes a factor. If you only need a qualitative input (e.g. safe or not safe) which does not rely on having a specific cut-off value then there is also no need to put in numeric values with that degree of accuracy.

Most often there will be a combination of use cases and level of accuracy required for those use cases. So you generally need to cater for the most common or critical tasks.