Schedule Forecasts in Project Management

One of the primary jobs of a project manager is to make predictions. It’s your responsibility to figure out what it will take to complete a project efficiently and effectively. Project Management Professional (PMP)^® credential holders are constantly asked to make accurate scheduling predictions — and adjust them as needed. This skill helps you keep the project on track and within budget. Learning how to create an accurate schedule forecast is part of that skill.

On this page:

What is a Schedule Forecast in Project Management?
How are Schedule Forecasts Created?
Factors That Can Affect Schedule Forecasts

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What is a Schedule Forecast in Project Management?

A schedule forecast estimates how long it will take to complete a project based on the information available at a given moment in time. The person creating the schedule should never make a random guess. Instead, they use a variety of tools and knowledge sources when making their predictions and revise them as the project evolves, and criteria change.

Estimating the project schedule accurately is essential for the project’s and the project manager’s success. Much can happen to threaten the workflow once the project is underway. If the forecast is wildly off, the project may be canceled or incomplete when workers fail to meet deadlines and produce deliverables.

Forecasting also offers additional benefits for project managers. It helps you plan for unknown factors that can throw the project off course. Specifically, you can improve decision-making and cash flow planning, lower costs, and spot resource gaps and threats that can slow down the workflow.

Understanding the schedule forecast is an important skill for project managers or PMP credential holders to master in order to keep their projects on schedule and within budget.

How are Schedule Forecasts Created?

Schedule forecasts rely on the use of three key factors: the project baseline, task dependencies, and snapshot baselines. The project manager considers due dates, whether tasks can be worked on simultaneously or must be completed in stages, and how work progresses throughout the project.

Project managers use several forecasting techniques, including the following:

Trend analysis. With this technique, you use data from previous projects to predict needs for the current one. It requires some understanding of both projects so you can choose which past trends are most relevant under the current circumstances. This gives you a very rough estimate of what may happen, so be prepared to revise projections as you gather more data throughout the project.
Time series analysis. Historical data can be more valuable when you break it down and look at it from multiple perspectives. Time series analysis lets you view past project data through random variations like seasonal trends. This can help you identify the different factors affecting outcomes and increase the accuracy of your forecast.
What-if scenarios. Using a what-if scenario is an excellent tool for understanding the relationships between people and tasks and how they affect each other. For example, you may consider how offering workers more money to complete tasks may boost production or how the boost in production may affect the overall quality. This tool lets you consider multiple outcomes and creates a framework for explaining these possible outcomes to stakeholders.

Project Managers, PMI-SP’s, and Project Management Professionals (PMP) should have a solid understanding of how to create an accurate schedule forecast. This includes knowing what factors affect the outcome, which tools and techniques to use, and how to revise the forecast as new information becomes available.

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Factors That Can Affect Schedule Forecasts

The challenge of schedule forecasting is identifying which factors will affect the project’s schedule. Some of these factors are easier to detect than others, and they can change during the course of the project. For example, a key piece of equipment may malfunction during the project. The work may stall until the crew has a replacement. Here are more factors to consider when creating a schedule forecast:

Data accuracy. If the data is flawed, the forecast is also flawed.
Experience. The more practice you have working with a schedule forecast, the easier it is to work with them. You can expect to work with a schedule forecast if you’re in the field of project management, such as a certified PMP or PMI-SP.
Project type. Some projects are more challenging to schedule than others. For example, a project that requires skilled workers, specialized equipment, or materials subject to wild price fluctuations may not be as easy to predict.
Project complexity. A job with multiple dependent tasks can be more challenging to forecast because an issue with an early task can have cascading effects on the remaining tasks.
Update frequency. If you wait too long to update the schedule forecast, you may spend time sorting through an excessive amount of data that slows your ability to make decisions. All professionals who handle project schedules, such as a PMP or PMI-SP, should make it a habit to update their schedule forecast
Detail level. The more information you include in the forecast, the more time you spend creating and updating it.
Use of probabilistic methods. Organizations that use probabilistic methods for forecasting see a greater return on their investment than the rest.
Resource availability. Access to the resources you need to complete the project directly affects how quickly and when it can be completed.
Number of workers. The number of workers you have — and their skill levels and knowledge — affect the length of time needed to complete a project.
Project location. The location of a project can introduce environmental and legal factors to the mix. For example, state or local laws may restrict activities or require additional steps like getting a permit to work in a specific area.
Economic climate. The strength of the economy can affect the cost of materials, supply chain issues, and the pool of available workers.

As a project manager, one of your top goals is improving productivity and performance so you can deliver the goods to the customer on time. Schedule forecasting is more than choosing a completion date. It requires experience with forecasting techniques, understanding all the factors that can affect the project schedule, and the ability to revise and adjust the schedule as the variables change.

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Author profile

Erin Aldridge, PMP, PMI-ACP, & CSPO

Director of Product Development at Project Management Academy