How to display Infinity to users

Question

I'm designing an interface that displays a table to users with marketing spend and conversions on that marketing spend.

The table is something like this:

<table>
  <tr>
    <th>Spend</th>
    <th>Conversions</th>
    <th>Cost per Conversion</th>
  </tr>
  <tr>
    <td>$45.92</td>
    <td>231</td>
    <td>$0.20</td>
  </tr>
  <tr>
    <td>$22.12</td>
    <td>0</td>
    <td>{{?}}</td>
  </tr>
</table>

The table is populated by JavaScript, which calculates the conversion rate dynamically.

When the JS runs into the third row, I end up with the string "Infinity" displaying for the conversion rate due to the divide by zero that happens (22.12/0)

What I'm wondering is, from a user experience perspective, what should I display there? These are users, not mathematicians, so using the Infinity symbol would confuse them and using 0 would portray the incorrect data.

Well, if not infinity or zero, what do you want to display there? — j08691, May 05 '14 at 19:28
The title of this question is a bit misleading.. I answered it bit too early suggesting to use `∞` html entity for displaying infinity to user :/ — Prasanth, May 05 '14 at 19:32
possible duplicate of [Infinity symbol with html](http://stackoverflow.com/questions/2254913/infinity-symbol-with-html) — Mike Samuel, May 05 '14 at 20:06
@j08691 I tend to categorize issues of user experience in design as programming questions, but perhaps you know of somewhere better to put this question in the StackExchange network, or elsewhere? — Dave Long, May 05 '14 at 20:53
@j08691: sorry, I didn't know that ux.stackexchange.com existed. — Dave Long, May 07 '14 at 16:28

Jonathan M · Accepted Answer · 2014-05-05T19:36:42.670

5

Because your users are business folks wanting to know their advertising conversion rate, and none is available since there were no conversions, I would suggest:

n/a

By the way, as I see it, you're not giving them conversion rate per se. You're giving them cost per conversion, which should then be displayed in dollars, not a percent sign. That is, your first row should be $0.20 instead of 20%.

Conversion rate is the number of people that converted (or took action) divided by the number of people that viewed the ad. That would indeed be a percentage.

edited May 05 '14 at 19:36

answered May 05 '14 at 19:29

Jonathan M

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Yes sorry. I mean Cost per Conversion – Dave Long May 05 '14 at 20:49
The problem with using N/A is what it stands for. Technically, in cases where you are spending money but not converting, the cost per conversion is not applicable, but in the real world, it is very important. N/A drives the user to think, "Well it's not applicable, so I don't need to care." – Dave Long May 05 '14 at 20:51
I was meaning "not available", which is another oft-used meaning: http://en.wikipedia.org/wiki/N/a – Jonathan M May 06 '14 at 00:26

score 1 · Answer 2 · edited Jun 20 '20 at 09:12

1

I end up with the string "Infinity" displaying for the conversion rate due to the divide by zero that happens (22.12/0)

What I'm wondering is, from a user experience perspective, what should I display there?

If the problem is that you have a nonsensical result because the number of conversions is zero, then alert the user to that fact.

Display "no conversions" and maybe distinguish it from the rest of the table by using a different style (or audible cue for screen readers).

If you don't want to change the layout of the table, then maybe an infinity symbol with a reference to a footnote like:

$12.34 0 ∞₁

Cannot calculate rate because no conversions occurred.

edited Jun 20 '20 at 09:12

Community

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answered May 05 '14 at 20:10

Mike Samuel

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The footnote is a nice touch, but footnote numbers are usually superscripted¹, not subscripted². (¹ Even in layman's work. ² That's reserved for the ol' H₂O.) – Jongware May 05 '14 at 20:26
@Jongware, Your meta-footnote deserves a ⁺¹ – Mike Samuel May 05 '14 at 21:04

score 0 · Answer 3 · answered May 05 '14 at 19:44

0

Maybe "not a number"? (NaN in programming).

answered May 05 '14 at 19:44

nicael

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How to display Infinity to users

3 Answers3