A schedule or timetable is a basic time management tool consisting of a list of times at which possible tasks, events, or actions are intended to take place, or a sequence of events in the chronological order in which such things are intended to take place. The process of creating a schedule - deciding how to order these tasks and how to commit resources between the variety of possible tasks - is called scheduling, and a person responsible for making a particular schedule may be called a scheduler. Making and following schedules is a fundamental human activity, and learning to do these things effectively is one of the most basic life skills. There are a wide variety of situations in which schedules are necessary, or at least useful.
Schedules are useful for both short periods, such as a daily or weekly schedule, and for long term planning with respect to periods of several months or years. They are often made using a calendar, where the person making the schedule can note the dates and times at which various events are planned to occur. Schedules that do not set forth specific times for events to occur may instead list an expected order in which events either can or must take place.
Kinds of schedules
Publicly available schedules
Certain kinds of schedules reflect information that is generally made available to the public, so that members of the public can plan certain activities around them. These may include things like:
- Hours of operation of businesses and government offices, which allow consumers of these services to know when they can obtain them.
- Transportation schedules, such as airline timetables, train schedules, bus schedules, and various public transport timetables are published to allow commuters to plan their travels. From the perspective of the organization responsible for making transportation available, schedules must provide for the possibility of schedule delay, a term in transport modeling which refers to a difference between a desired time of arrival or departure and the actual time. Despite the use of "delay", it can refer to a difference in either the early or late direction.
- In broadcast programming, the minute planning of the content of a radio or television broadcast channel, the result of that activity is the generation of a list of shows to be broadcast at regular times or at specific times, which is then distributed to the public so that the potential audience for the show will know when it will be available to them.
- Concerts and sporting events are typically scheduled so that fans can plan to buy tickets and attend the events.
An internal schedule is a schedule that is only of importance to the people who must directly abide by it. It has been noted that "[g]roups often begin with a schedule imposed from the outside, but effective groups also develop an internal schedule that sets goals for the completion of micro-tasks". Unlike schedules for public events or publicly available amenities, there is no need to go to the time and effort of publicizing the internal schedule. To the contrary, an internal schedule may be kept confidential as a matter of security or propriety.
An example of an internal schedule is a workplace schedule, which lists the hours that specific employees are expected to be in a workplace, ensure sufficient staffing at all times while in some instances avoiding overstaffing. A work schedule for a business that is open to the public must correspond to the hours of operation of the business, so that employees are available at times when customers are able to use the services of the business. One common method of scheduling employees to ensure the availability of appropriate resources is a Gantt chart. Another example of an internal schedule is the class schedule of an individual student, indicating what days and times their classes will be held.
Project management scheduling
A schedule may also involve the completion of a project with which the public has no interaction public prior to its completion. In project management, a formal schedule will often be created as an initial step in carrying out a specific project, such as the construction of a building, development of a product, or launch of a program. Establishing a project management schedule involves listing milestones, activities, and deliverables with intended start and finish dates, of which the scheduling of employees may be an element. A production process schedule is used for the planning of the production or the operation, while a resource schedule aids in the logistical planning for sharing resources among several entities.
In such cases, a schedule "is obtained by estimating the duration of each task and noting any dependencies amongst those tasks". Dependencies, in turn, are tasks that must be completed in order to make other tasks possible, such as renting a truck before loading materials on the truck (since nothing can be loaded until the truck is available for things to be loaded on). Scheduling of projects, therefore, requires the identification of all of the tasks necessary to complete the project, and the earliest time at which each task can be completed. In creating a schedule, a certain amount of time is usually set aside as a contingency against unforeseen days. This time is called scheduling variance, or float, and is a core concept for the critical path method.
Scheduling is important as an internal process in computer science, wherein a schedule is a list of actions from a set of transactions in databases, and scheduling is the way various processes are assigned in computer multitasking and multiprocessing operating system design. This kind of scheduling is incorporated into the computer program, and the user may be completely unaware of what tasks are being carried out and when. Scheduling operations and issues in computing may include:
- The operation of a network scheduler or packet scheduler, an arbiter program that manages the movement of certain pieces of information in the computer.
- Open-shop scheduling, Job Shop Scheduling, Flow Shop Scheduling Problem, optimization problems in computer science.
- I/O scheduling, the order in which I/O requests are submitted to a block device in operating systems.
- Job scheduler, an enterprise software application in charge of unattended background executions.
- See Hojjat Adeli, Asim Karim, Construction Scheduling, Cost Optimization and Management (2003), p. 54.
- Ofer Zwikael, John Smyrk, Project Management for the Creation of Organisational Value (2011), p. 196: "The process is called scheduling, the output from which is a timetable of some form".
- Phyllis Kohl Coston, Celebration of Success (2013), p. 26.
- Dennis Coon, John Mitterer, Psychology: Modules for Active Learning (2007), p. 7.
- Michael E. Gorman, Transforming Nature: Ethics, Invention and Discovery (1998), p. 308.
- Calin M. Popescu, Project Planning, Scheduling, and Control in Construction (1995), p. 522.
- Project Management Institute. A Guide to the Project Management Body of Knowledge (PMBOK Guide). Project Management Institute, 4 Original edition (December 31, 2008).
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