What Is the Difference Between a Schedule and a Prediction?
From the earlier reference collection. Read the current software blog.
A schedule states a planned time; a prediction estimates when a vehicle is likely to arrive based on current information.
The schedule is the plan
A scheduled arrival is the time published as part of a timetable. It answers: what time does the service plan to reach this stop? For example, a timetable might list a 7:42 arrival. That value remains the planned time even if traffic, a late departure, or an operational change affects the actual trip.
Schedules are useful for planning and for understanding the service pattern. They are not proof that a vehicle is currently on time. A static timetable may be the only information available, and readers should be able to recognize it as planned data.
A prediction estimates the future
A prediction is an estimate of a future event, such as an arrival expected in about six minutes. It can change as the vehicle moves or as new information becomes available. If the schedule says 7:42 and a live estimate says 7:49, the two values describe different things: the planned arrival and a current estimate.
The word “prediction” does not guarantee certainty. It can be wrong, stale, or unavailable. A useful interface therefore labels the value and may indicate when it was last updated, rather than presenting an estimate as if it were the published timetable.
Compare like with like
Suppose a rider checks at 7:38. The schedule says 7:42, while a prediction says 7:46. The schedule indicates the planned time; the prediction suggests a later arrival is currently expected. Displaying only “7:46” without identifying its source leaves the rider unable to tell whether it is an estimate or a revised published time.
When evaluating reliability, compare an observed or estimated arrival with the scheduled value for the same trip and stop. Do not compare an estimate for one vehicle with another trip’s timetable entry. Also keep the date and local time context attached, especially around midnight.
Make the distinction visible
Use labels such as “Scheduled” and “Estimated” beside values, and keep their visual treatment consistent. If the prediction disappears, retain the scheduled time when available and explain that a live estimate is not currently shown.
This small distinction supports better decisions. A schedule gives a stable reference for what was planned; a prediction gives a changing view of what may happen next. Showing both clearly lets riders use each for the question it can answer.