How can I visualize that data for a cell is not applicable?

Question

Let's say I have a data table of students:

Name   | Birthdate  | Exit of school | Average Grade
----------------------------------------------------
Alice  | 01.02.2010 | 23.10.2017     |          1.2
Bob    | 28.04.1990 | 08.10.2011     |          1.7
Charlie| 28.02.2015 |     N/A        |          1.5 

Charlie did not exit school so far, so this is not available.

What are design options / considerations to show this?

I see the following alternatives:

• Leaving the cell empty
• Putting - (many options here) inside the cell
• Putting N / A inside the cell
• Filling the cell in black
• Putting a diagonal line from lower left to top right in the cell

Are there any advantages / disadvantages of the options? Are there other options?

Answer 1

Like you mentioned with the hyphen, I would approach this as I would a résumé or CV

If a course or job I'm doing is current/ongoing I simply use a hyphen ( - ) or In Progress.

For example,

Name   | Birthdate  | Exit of school | Average Grade
----------------------------------------------------
Alice  | 01.02.2010 | 23.10.2017     |          1.2
Bob    | 28.04.1990 | 08.10.2011     |          1.7
Charlie| 28.02.2015 |  In Progress   |          1.5

I think N/A would imply that the date is unknown.

Answer 2

Just like you have it now.

Using N/A is very known and common. Also, it literally answers your question How can I visualize that data for a cell is not applicable?: and the simple answer is: "add not applicable to that cell". After all, if students didn't exit school, then there's no data to apply since it doesn't even exist. Options like "in Progress" would mean an exit is happening, when an exit is an absolute date by definition, it can't be relative or abstract. Leaving the cell empty would be really confusing, same for a hyphen or a diagonal line. All these options are ambiguous and ambivalent. N/A means N/A, which is short for absence of data

By using N/A, you also add a visualization factor: quick scan of information.

From Simplify UI Data Visualizations – in 7 Simple Steps

Less is definitely more.

All of these small design tweaks work together to separate things visually, which allows people to scan, identify and associate more quickly. Faster cognition means greater understanding, which means what’s there is infinitely more valuable.

Remember that people have to be able to draw conclusions and act on what they see. When the cognitive effort required to do that is high, people struggle to make sense of it all.

As you can see, the N/A option fits just perfect: easy to understand, simple, easy to scan, no additional cognitive load

just take a look at how easy is to scan N/A at first sight when you have more data:

A caveat

If you feel like N/A might be not understood by some users (very unlikely, but still), simply add a reference on top of your table: N/A= Not Applicable

Answer 3

I would also leave N/A there. I like what wikipedia does - the N/A has a different background, so it's immediately obvious that the value is different from the others. You can also add a tooltip with "Not applicable" in case you worry people might not understand it.

Source: https://en.wikipedia.org/wiki/Great_Britain_at_the_2016_Summer_Olympics

Answer 4

Leave it NULL, as in nothing in the cell. It's easier to distinguish which students have not exited the school, especially when you have a long list of students. NULL values in date columns is also how it is stored in the database.