Schedule Version Comparator

“Why did the date move?”

A finish date that moves between two monthly updates has a cause, and it is almost never one thing. A predecessor finished late. Work that was due to start did not. Someone lengthened a duration, added a link, changed a lag, or added an activity. Scheduling software shows the new date; it does not say which of those changes produced it. This tool compares the two versions activity by activity and walks the new critical path from its start, naming what changed, slipped or was added at each step, so the slip can be traced to where it began.

Every change, not just the dates

Activities added, deleted and renamed; durations changed; links added, deleted or retyped; constraints moved. Changes to a schedule’s logic are the ones most easily missed and the ones that move dates most, and some are made deliberately to hide a slip: a link removed so that a late activity stops driving the finish. All of them are listed.

History that changed

An actual start or finish is a record of what happened. If it differs between two versions, somebody changed the past, sometimes to correct a mistake and sometimes not. Rewritten actual dates are listed separately, in red, because they are worth a question.

Against the baseline

With one file that carries a baseline, the second tab compares every activity’s forecast or actual finish with its baseline finish, in working days, and shows which are late, early or on time, and which were added after the baseline was set.

What this does not do

It matches activities by their unique IDs, so an activity deleted and re-added under a new ID looks like two separate changes. It schedules both versions with this site’s own critical path calculation, which makes them comparable with each other but can differ slightly from the software that saved them. And it finds causes in the files; it cannot say whether a change was justified. That conversation is the reason to run it.