IB Docs (2) Team
BMT 9 - Gantt chart (HL only)
"If it wasn't for the last minute, nothing would ever get done."
- Rita Mae Brown, American novelist and poet
A Gantt chart is used as a visual organizational planning and decision-making tool to show the sequence and schedule of all the different tasks for a certain project. The idea was created by American mechanical engineer and management consultant Henry L. Gantt (1861 - 1919).
A Gantt chart organizes all the tasks of a project into chronological order, and identifies any tasks that can be done concurrently in order to minimize the time needed to complete the project. Scheduling individual tasks also enables managers to have better project management, in terms of monitoring and control. Essentially, the tool enables managers to identify the fastest time in which a project can be completed if the individual tasks are well-planned and executed effectively.
To construct a Gantt chart, several steps are necessary:
Identify all the various tasks, plus the duration, that need to be completed, arranging these in chronological order.
Identify any tasks that can be completed concurrently.
Establish dependent tasks in order to sequence the various tasks, i.e., recognise which activities must be completed before the next one(s) can begin.
Determine how long the project should take to complete.
An example of a Gantt chart is shown below, which shows a simplified version of the activities needed for construction of an extension (enlargement) to an existing office building:
Activity | Proceeded by | Duration (weeks) |
A: Planning permission | - | 4 |
B: Hire contractor | A | 1 |
C: Hire interior designer | A | 1 |
D: Construction work | B & C | 7 |
E: Painting & decorating | D | 2 |
F: Fixtures | D | 2 |
G: Furnishing | E | 2 |
H: Pre-launch checks | G | 1 |
The Gantt chart can then be illustrated or presented as follows:
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Note that the project, when presented in the format a Gantt chart shows the project can be completed in 17 weeks. If the tasks were done individually without planning, the sum of the separate tasks equals 20 weeks.
Typically, managers will shade in (manually on a display board, or via computer software) the Gantt chart to indicate the level of progress. For example, the shading shown here indicates the activity has been half completed:
Advantages of Gantt charts
The advantages of using Gantt charts as a Business Management tool to support organizational planning and decision-making include:
A Gantt chart helps project managers to have a clear overview of the whole project, in terms of timing and resourcing needs.
It helps to identify the minimum amount of time required to complete a certain project.
It helps managers to identify which tasks can take place at the same time, thereby making efficiency gains.
As a visual planning tool, it provides a clear representation of the current progress of each task in a project.
Gantt charts can be used for many different scenarios for scheduling and project management purposes.
Realistic deadlines can be set and resourcing needs (such as people, machinery, and finance) can be arranged for the various tasks of a project.
The Gantt chart enables managers to prioritise and commit resources to tasks that are most time sensitive or urgent.
Disadvantages of Gantt charts
However, there are also shortcomings of Gantt charts as an organizational planning and decision-making tool. These limitations include:
The usefulness of a Gantt chart is dependent on the accuracy of the information used to create it. Inaccurate and unrealistic schedules make Gantt charts rather meaningless.
The length of each bar indicates the expected duration of the task only; it does not show the amount of work involved or the amount of resources required for each of these activities.
Gantt charts are not prescriptive nor precise, so need to be constantly monitored and updated accordingly. For example, a delay in one task will have knock-on effects on all activities that follow.
Gantt charts are meant to be simplistic (their strength), but this means that complex projects with interconnected tasks can be problematic to display succinctly on a Gantt chart.
Watch this 5 minutes video which explains how Tesla builds its "giga" factories so rapidly:
Students should consider how Gantt charts could be used to ensure timely completion of the prefabricated production / construction and design techniques. Also, consider how the use of pre-made materials / components helps in reducing transportation costs / time, assembly and production times, as well as to improving quality.
Watch this video to review your understanding of Gantt charts as a planning tool for business managers.
ATL Activity 1 (Thinking skills) - Management styles and decision-making
Read this excellent and informative article from the BBC here.
It also includes a short video clip about how chief executive officers (CEOs) make significant decisions.
Theory of Knowledge (TOK)
The use of decision trees, force field analysis, and Gantt charts as tools in the BMT all help managers to make decisions based on scientific and quantitative methods.
What role do intuition and emotions play in organizational decision making?
Case Study - Culture and decision-making
On 18th March 2010, the doors of Universal Studios Singapore were open to its first customers at precisely 8.28am.
This followed the 18 Chinese lions that paraded through the entrance at 8.08am.
The number 8 is considered highly auspicious in Chinese culture (the Chinese account for the largest ethnic group in Singapore).
ATL Activity 2 - The Wedding Planner
Recommended time: 50 mins (or complete as a Home Learning activity)
Your best friend (forever) is getting married!
Jot down 15 tasks / jobs / roles / activities that need to be completed in order to have the perfect wedding for your best friend
Examples might include: securing a suitable venue, sending out invitations, getting the custom-made wedding dress and so forth
Determining the order in which the 15 tasks need to be done (with 1 being the first task and 15 being the last task).
Your friend’s wedding is now exactly 10 months away. Create a Gantt chart illustrating the 15 tasks from today until the actual wedding day. Things to consider might include:
What are the dependencies (the order in which tasks must take place)?
Are there any tasks that can take place simultaneously?
How would you deal with any free time between tasks to ensure efficient use of the limited time you have to organize the whole wedding?
Present your Gantt chart to the class and include a judgement about how useful you found the tool to be in planning and scheduling this project for you very best friend.
ATL Activity 3 (Thinking and Communication skills) - Producing Gantt charts
Think about a major piece of IB assessment that you have coming up, such as the Business Management IA, your prescribed TOK essay, your CAS Project, or the Extended Essay. Think of the different tasks involved in the completion of this piece of assessment and produce a Gantt chart to show the different activities and predicted time lines.
Be prepared to explain to your teacher and the rest of the class how this Gantt chart can help you with your IB assessments.
Top tip!
As with all quantitative techniques, the value of Gantt charts depends on the underlying data collected and used. When evaluating the use of Gantt charts, consider what the data do not reveal, and not only the outcomes shown by the tool for a particular situation or project.
Top tip!
Whilst it is possible that students can be asked to construct a Gantt chart in the examinations, it is (statistically) more likely that they will be asked to discuss the value of the tool (considering both the advantages and limitations/drawbacks of the tool). This is because it can be too time consuming to ask students to construct a Gantt chart from scratch under exam conditions (for the same reason that students are not required to construct a critical path or network diagram).
Instead, a Gantt chart might be presented in the stimulus and students are asked to use the chart to address a particular question and/or to evaluate its merits as a planning tool.
(a) Explain the purpose of Gantt charts as a business management planning tool. [4 marks]
(b) Explain one benefit and one limitation of using Gantt charts as a business management planning tool. [4 marks]
Teacher only boxAnswers
(a) Explain the purpose of Gantt charts as a business management planning tool. [4 marks]
A Gantt chart is a visual business management planning tool that shows the various tasks and timings of a project. It enables managers to plan and schedule the resources required to complete the project and to monitor its progress to prevent delays.
A Gantt chart is used to provide project managers with an instant overview of the various steps and stages of a project to minimize or eliminate inefficiencies for the successful completion of a project. It enables project managers to identify which activities are critical (these deadlines cannot be missed without causing the whole project to be delayed), thereby ensuring the project is also completed within the designated budget.
Award [1 - 2 marks] for an answer that shows some understanding of the demands of the question, although the explanation lacks depth.
Award [3 - 4 marks] for an answer that shows good understanding of the demands of the question. The explanation is thorough, and there is appropriate and effective use of terminology throughout the response.
(b) Explain one benefit and one limitation of using Gantt charts as a business management planning tool. [4 marks]
Possible advantages include an explanation of any one of the following points:
A Gantt chart provides a clear picture of the entire project, so it can be resourced and completed efficiently.
The tool provides a clear visual representation of the current progress of each task in the project.
It provides flexibility for project managers.
Gantt charts can be applied to a large variety of projects.
Accept any other relevant advantage that is clearly explained.
Possible disadvantages include an explanation of any one of the following points:
The tool is based on estimates of tasks and their respective timings to complete all of the various tasks; this often proves to be inaccurate in reality, causing delays to the completion of the project.
It can be difficult to plan and follow the Gantt chart when used for very large and complex projects across multiple teams and/or locations. Whilst computer software can mitigate this to a large extent, the tool can still remain complex to manage overall.
The tool and its outcomes are based largely on qualitative considerations, and does not reveal the financial implications, such as costs and other quantitative data.
The focus is on deadlines, which may diminish the quality of output if tasks are rushed to complete the project on time.
Accept any other relevant advantage that is clearly explained.
Mark as a 2 + 2
Award [1 mark] for each point, and a further [1 mark] for a clear and accurate explanation.
Dorsett Construction Co. has been appointed to renovate the offices of a client.
a. Describe the meaning of Gantt charts. [2 marks]
b. Draw a Gantt chart from the data below for the project. [4 marks]
Activity | Order | Duration (weeks) |
A | - | 2 |
B | A | 4 |
C | A | 3 |
D | B | 2 |
E | C | 1 |
F | D & E | 2 |
Teacher only boxAnswers
a. Describe the meaning of Gantt charts. [2 marks]
A Gantt chart is a visual organizational planning and decision-making tool used to show the sequence and schedule of all the different tasks for a certain project.
Award [1 mark] for a description that shows limited understanding of a Gantt chart.
Award [2 marks] for an accurate description that shows good understanding of a Gantt chart, similar to the response above.
b. Draw a Gantt chart from the data below for the project. [4 marks]
Gantt chart for Dorsett Construction Co.
Award [1 – 2 marks] for a Gantt chart that shows some understanding in scheduling, although there are two or more errors.
Award [3 – 4 marks] for a Gantt chart that shows a good level of understanding of scheduling, including the correct unit of measurement (number of weeks to complete the project). Award [3 marks] if there is one error from the Gantt chart.
TST Education publishes educational textbooks for university students. The typical publication goes through the following process.
Activity | Order | Duration (months) |
A | - | 1 |
B | - | 2 |
C | A | 3 |
D | B | 4 |
E | C & D | 1 |
F | E | 2 |
G | E | 2 |
H | G | 1 |
I | F & H | 2 |
Use the information in the table to construct a Gantt chart for a typical publication project of TST Education. [4 marks]
Teacher only boxAnswer
Gantt chart for TST Education
Award [1 – 2 marks] for a Gantt chart that shows some understanding in scheduling, although there are two or more errors.
Award [3 – 4 marks] for a Gantt chart that shows a good level of understanding of scheduling, including the correct unit of measurement (number of weeks to complete the project). Award [3 marks] if there is one error from the Gantt chart.
Teachers can download a PDF version of Exam Practice Questions 2 and 3 by clicking the icon below and use this with their students in class.
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