Activity A task or unit of work within a project or group of
projects which usually:
- has a specific duration
- has a logical relationships to other tasks (or activities) in
a project.
- makes use of resources (e.g. people, materials, facilities)
- has a cost that can be related to it
Activity status An activity's status can be:
- Planned or Scheduled (not started and not on the critical
path)
- Critical (not started but on the critical path)
- Started or Working (started and not finished)
- Actual or Finished (completed)
Activity-on-Arrow Technique
A form of criticaActivity-on-Arrow Technique l path analysis
diagram where activities (tasks) are represented by arrows and the
start or finish of activities (tasks) are represented by numbers
within circles or similar shapes.
Activity-on-Node Technique
A form of critical path analysis diagram where (tasks) are
represented by rectangular boxes (nodes) which contain information
about the tasks. Sometimes called 'Precedence Networking'
Actual activity
'Real' or 'existing' activities (tasks) that have been
completed before the project was last updated or scheduled
(usually today's date).
Actual Cost of Work Performed (ACWP)
Actual cost of an activity, group of activities (tasks) or a
whole project. When compared to BCWP, permits financial monitoring
of project progress
Actual date
Dates on which something actually happens - e.g. the start
or finish of a task. Actual dates override all other scheduling
constraints.
Actual duration
The calculated or scheduled time between the early start and
early finish of a task. All tasks have an actual duration whether
they are completed or not.
Alternate resource
A resource that may be substituted when resource scheduling
- if the requested resource is not available.
Archiving
Saving the current start and finish dates of tasks so they
can be compared with dates from later schedules. Producing
archives is a useful way of comparing actual progress to planned
progress. Archives are also referred to as "Baselines".
As-Late-As-Possible (ALAP)
An task for which the user requires the early dates to be as
late as possible without delaying the early dates of any following
tasks.
As-Soon-As-Possible (ASAP)
Usually the default status of an Task - where the user
requires the early dates to be as soon as possible.
Availability
The quantity of a resource available at a given time (rather
than the quantity needed to complete an Task).
Availability limit
A limit applied to a resource which resource and duration
schedule engines use when attempting to schedule within normal
resource or total resource limits.
Backward Pass
A project scheduling process which determines the latest time
that tasks must start and finish if a project is not to be delayed.
Bar Chart
A report format where bars indicate the timing and sequence
of tasks (sometimes called a Gantt chart)
Bar Chart Symbols
Characters or symbols used in place of the horizontal bar in
a bar chart which may be used to provide additional information
(e.g. the status of an Task)
Baseline
A copy of the project schedule for a particular time
(usually before the project is started) that can be used for
comparison with the current schedule.
Budget
The planned cost for an Task or project.
Budget at Completion (BAC)
The total budget for a project, or part of a project.
Budgeted Cost of Work Performed (BCWP)
The budgeted cost of a project or part of a project -
sometimes called 'earned value'. When compared to ACWP, permits
financial monitoring of project progress
Budgeted Cost of Work Scheduled (BCWS)
The cost that should have been achieved according to the
project baseline dates. When compared to ACWP it is possible to
determine if the project is ahead of or behind schedule.
Calculate a network
Produce a time schedule for a 'network' of tasks within a
project or group of projects.
Calendar
A calendar is a specific combination of days per week,
shifts per day and shutdowns. Projects can have a number of
calendars to accommodate tasks that work different days and hours.
Cost variance
The difference between the budgeted and actual cost of work
performed (BCWP - ACWP).
Critical task
If the latest an activity can start is the earliest it must
start, it is critical. Critical tasks show the same early and late
dates on the forward pass as on the backward pass and in normally
have no float.
Critical path
The longest path(s) through a 'network' of inter-dependent
tasks. If any activity on the critical path is delayed, the entire
project will be delayed. Many projects have more than one critical
path.
Critical path analysis
The project planning process in which activity critical
paths are determined using activity-on-node (precedence
networking) or activity-on-arrow techniques.
Dependency
The relationship between two interdependent tasks in a project
or series of projects.
Discontinuous activity
An activity (task) in which the time between the start and
finish dates is exceeds its 'real' duration. Usually created in
order to satisfy start-to-start and finish-to-finish relationships
with other activities (tasks).
Dummy activity
Used to describe an activity which takes zero time to
complete or has no work content.
Duration
The scheduled time for an activity to be completed.
Duration scheduler
A project scheduling process that shows activity dates,
float and the critical path as a time schedule while also taking
account of a project's resource requirements and availabilities.
Optimises activity durations in order to maximise the use of
resources.
Earliest feasible date
The earliest date on which an activity could be scheduled to
start based on the scheduled dates of all its predecessors (in the
absence of any resource constraints on the activity itself).
Calculated by resource scheduling.
Early dates
The earliest dates on which an activity can start and finish
(determined by forward pass of time analysis).
Early finish
The earliest dates that an activity can finish without
affecting the project duration or activity inter-dependencies.
Early start
The earliest an activity can start without affecting the
project duration or activity inter-dependencies.
Earned value
The budgeted cost of a project or part of a project which
compared to ACWP, permits financial monitoring of project
progress. Sometimes called Budgeted Cost of Work Performed (BCWP).
Estimated Duration
The most accurate and realistic estimate of the duration of
an activity.
Finish-to-Finish (FF) Link
A relationship between two tasks where the second cannot
finish until the first has finished.
Finish-to-Start (FS) Link
A relationship between two tasks where the second cannot
start until after the first has finished.
Float
The difference between the time necessary to complete an
activity and the time available.
Forward Pass
A project scheduling process in which all activity durations
are added up to find the shortest possible project duration and
the early start and early finish dates of tasks.
Free Float
The maximum amount by which an activity can be delayed
beyond its early dates without delaying any succeeding activity
beyond its early dates.
Hammock activity
An activity which represents a group of (tasks) and which has
a start-to-start link with the first in the group and a
finish-to-finish link with the last. A hammock activity usually has
an estimated duration of zero and has no links with other activities
(tasks).
Hierarchical Coding Structure
A multi-level coding system for tasks in which every code
except the one at the top has a 'parent'.
Internetwork link
A logic link between tasks in different projects or
'networks'..
Key activity
duration and are sometimes known as 'milestone' tasks.
Ladder activities
A series of activities (tasks) running in parallel, each
linked by a start-to-start and finish-to-finish link.
Lag
A time delay associated with a relationship between tasks in
a project - described as either positive or negative. Negative lag
is sometimes called "lead."
Lag Link
A finish-to-finish link between tasks.
Late dates
The latest dates on which an activity can start and finish.
Determined by a backward pass time analysis.
Late finish
The latest time an activity can finish without delaying a
project.
Late start
The latest time an activity can start without delaying a
project.
Lead link
A start-to-start link.
Leading activity
An activity without any preceding activity.
Logic delay
The period of time between two linked tasks. (e.g. a coat of
paint is one activity and the paint has to dry before the next
activity can start).
Logic delay calendar
The calendar which the logic delay must obey. Unless a
calendar is specified, the delay follows the calendar of the
succeeding activity.
Logic Loop
A logic loop occurs in a project when two or more tasks are
mutually dependant. The result is that a forward pass cannot be
performed.
Management Code
A code system which assigning codes to tasks in order to
reflect the management needs of business(es) in the preparation of
reports etc.
Milestone
See Key Task
Negative Float
Occurs when target dates cannot be scheduled within the
specified activity durations and shows the time by which the early
date of an activity exceeds its late date.
Network analysis techniques
A general term referring to a variety of planning techniques
- e.g. precedence networking, activity-on-arrow, line-of-balance.
Network diagram
A diagram showing the tasks in a project, their sequence and
the relationships (links) between them - a 'model' of the project.
In the commonly used precedence diagram, tasks are represented by
nodes and links are represented by lines. Sometimes called a
flowchart, PERT chart, logic drawing, or logic diagram.
Network logic
The logic of a 'network' of tasks within a project describes
the order in which tasks in a network are performed and the
relationships (links) between the tasks.
Node
A rectangular box in a network which contains information
about one activity, e.g. the number and description.
Organizational Breakdown Structure (OBS)
A hierarchical structure designed to pinpoint the area of an
organization responsible for each part of a project.
Physical Percent Complete
The percentage of the work content of an activity that has
been achieved.
Plan
A scheme for accomplishing a goal which describes how the
goal will be achieved.
Precedence Diagram Method (PDM)
One of the two methods of representing projects as networks
of tasks in which the tasks are represented by nodes and the
relationships between them by arcs. (The other method - Arrow
Diagram, is rarely used.)
Precedence Networking
A form of critical path analysis in which tasks are
represented by nodes (rectangular boxes) and dependencies are
represented by lines. Also known as activity-on-node technique.
Precedent
Preceding activity.
Precedent Links
Links that define the relationships between tasks and those
that logically precede it.
Preceding Activity
An activity (task) that logically precedes another.
Preceding tasks (preceding tasks or precedents) can be linked to
those which logically succeed them (their successors) by a
finish-to-start, start-to-start or finish-to-finish links.
Preceding Float
Float that precedes an task's start date, i.e. the amount of
time available between when an task is due to start and when it
has to start to avoid delaying other tasks.
Project
A series of tasks having an overall objective where the
management of time and resources justifies formal planning.
Project Data
Data which relates to an individual project, e.g. activity
descriptions or durations.
Project Date
The project date is the date to which the project has been
updated, i.e. 'today's' date or 'time now' which remains current
until the project until another project date is entered.
Project structure
A term used to describe the system of dividing a project
into a master project and sub-projects or 'networks' of tasks.
While each sub-project is a project in its own right, it relates
directly to a single task in the master project.
Relationship
A logical connection between two tasks.
Remaining duration
The amount of work that remains to be completed after the
project date in respect of a task that has started.
Requirement
The quantity of a resource needed to complete a task (as
opposed to the quantity available, which is called the resource
'availability').
Resource
Anything required to carry out an task or project (except
time) - e.g. people, equipment, funding.
Resource breakdown structure
The hierarchical structure of resources that allows resource
reporting and scheduling at the detailed or summary levels.
Resource Histogram
A histogram showing project resource requirements, usage,
and availabilities against a time scale.
Resource Levelling
A project scheduling process that optimises resource
availabilities against resource needs without compromising task or
project completion dates.
Resource Pool
A higher level resource in a resource breakdown structure.
Resource scheduler
A project scheduling process which takes account of the
resource requirements and availabilities and shows dates, float
and the critical path like a time schedule. Some high-level
resource schedulers maximise resource use by altering the
durations of certain tasks.
Resource-limited Project
A project where the project duration is determined by the
quantity of the resources available.
Schedule
A schedule of dates produced by a scheduling 'engine' - e.g a
basic time schedule will show date and duration information, float
and target dates.
Schedule Dates
Start and finish dates calculated by the scheduling 'engine'
(which take into account resource constraints, project logic etc).
Schedule Variance
The difference between the budgeted cost of work performed
and the budgeted cost of work scheduled at any point in time (BCWP
- BCWS).
Scheduled activity
A task that has not started (i.e. its start date as derived
from the forward pass is later than the project date).
Scheduler
The scheduling 'engine' in project management software that
carries out time, resource, duration scheduling functions etc.
Shutdown
An irregular non-working period such as a holiday or a
closure for maintenance work. Regular non-working periods (e.g
weekends) are not shutdowns.
Skills
An attribute that can be assigned to a resource.
Start-to-Start (SS Link)
A relationship between two tasks which indicates that the
second cannot start unless the first has already started.
Sub-project
A group of tasks represented as a single task in a higher
level of the same project.
Succeeding activity
An activity (task) which logically succeeds another and can
be linked to it by finish-to-start, start-to-start or
finish-to-finish links.
Succeeding float
The time available between when a task is due to finish and
the time when it has to finish to avoid delaying other tasks.
Succeeding links
Succeeding links define the relationships between a task and
those which logically succeed it. Links can be finish-to-start,
start-to-start or finish-to-finish. In the case of a
finish-to-start link, the successor cannot begin until the
precedent has finished. In a start-to-start link, the successor
starts at the same time as the precedent. In a finish-to-finish
link, the successor finishes at the same time as the precedent.
Successors
Succeeding tasks
Target date
Dates imposed on a task or project by the user that do not
relate to the normal sequence or duration of tasks but determine
when a task can start or finish. Target dates are respected during
scheduling if possible.
Target finish
A task is scheduled to finish on its target finish (or
before) if the task durations and availability of resources (if
any) permit.
Target start
An rask is scheduled to start on and not before its target
start unless other logic constraints delay it into the future.
Task
See Activity
Time Analysis
An analysis of the logic of activity durations generated by
forward and backward pass scheduling which calculates the early
and late dates for each activity on a project.
Time scheduler
A project scheduling operation that shows dates, float and
the critical path taking into account time only (ignoring resource
requirements and availabilities). Will show the knock-on effects
of durations that tasks have on each other taking into account
links with other networks.
Time-Limited Project
A project in which time, rather than resources, is the major
constraining factor. Such projects must be completed by a specific
date and are completed by acquiring whatever resources are
necessary.
Total Float
The sum of the work periods by which a task can be delayed
without delaying project completion. A commonly used calculation
fot total float is: 'late finish - early start - duration +1' (one
extra time unit is added because the start and finish dates are
inclusive).
Trailing Activity
An activity (task) that has no successors.
Variance
A discrepancy between the actual and planned performance on a
project, either in terms of schedule or cost.
Work Breakdown Structure (WBS)
The breakdown of a project in terms of deliverables.
Working
If an task's status is 'working' it is currently being
performed (i.e. it has an actual start date but no actual finish
date).
