project management glossary

negative float

 Negative float indicates activities must start before their predecessors finish in order to meet a target finish date. All float is calculated when a project has its schedule computed. Negative float occurs when the difference between the late dates and the early dates (start or finish) of an activity are negative. In this situation, the late dates are earlier than the early dates. This can happen when constraints (Activity Target dates or a Project Target Finish date) are added to a project.

 Where a path in a network becomes hypercritical the activities on that path have float of less than zero. The quantity of float then indicates the amount of time which must be picked up in order to achieve an imposed date.

 The amount of time by which the planned duration of a sequence exceeds the time available before an imposed date. It typically occurs during project implementation when critical activities leading to a required date are completed late, or during planning when an initial version of the schedule does not fit the allotted time frame. The cure is revision of logic, decrease in subsequent durations (e.g. by "crashing") such as by increasing resources of a change in methods. Otherwise the end date must be changed.

negative total float

 Time by which the duration of an activity or path has to be reduced in order to permit a limiting imposed date to be achieved.