Which word best describes something opposite to "delay"?

My application displays a column which shows if tasks are delayed or not and how big the delay is. The delay may be positive (if a task is delayed) or negative (if it's on time). The time difference between now and the scheduled date is shown.

I'd like to describe this column in a short way. How to call something opposite to delay in this case? Ahead? Advance?

Solution 1:

It sounds like either "ahead/behind" or "early/late" would work for your purposes.

Solution 2:

Lead and Lag

Ahead of schedule is lead. Behind schedule is lag.

These words can be used as both nouns and verbs.

Please note, however, that these terms are both positive as opposed to the concept of positive being delay.

Lead and Lag are the terms used in planning and scheduling.

Solution 3:

What you are measuring is timeliness. If something is on time it's being delivered in a timely fashion; if it's delayed it's not timely.

As well as being on time, a task can be ahead of schedule, which indicates that it will be finished before its due-date. If it's on time, with (say) two days' work to do in the next two days, then it's not ahead — even though your application will show −2.

However while the concepts of "days to go till the deadline" and "days overdue" can be expressed by positive and negative numbers (either way round), if what you're after is a heading for the column then I'd suggest just T. This means that you could read it is "Task X is at T − 5" or five days till its due date, or "Task Y is at T + 2" meaning it's two days overdue. "T" used in this way means "the due date" or "the due time" and it's caricatured in rocket launch countdowns, "T minus 10, 9, 8..."

Solution 4:

For a scheduling application, the right word may be slack.

Solution 5:

I can't think of a single word that expresses this idea and where the meaning of the sign would be clear.

I think the best you're going to do is something like Charles W's suggestion: a two-word title like "Ahead/Behind" or "Early/Late". I'd add that you should probably give some notation to indicate which is a plus and which is a minus. Like, I'd probably make the heading "Ahead(+)/Behind(-)" (or the other way around, whichever way you want to express it).

If it's for technical people, it's common to refer to deviations as a "delta", so you could call it "Schedule Delta". But you'd still have the issue of clarifying whether a positive number means you're ahead or behind.

Unless you have an established convention, I'd make positive mean ahead of schedule, just because we normally think of positive numbers as being good and negative numbers as being bad. Not always, but usually.