How to Create Accurate Timelines for Projects
Freelancers, corporate, and agency individual contributors can benefit from learning how to make accurate timeline estimations for business endeavors. Poor time estimating is the root cause of 25% of failed projects (PMI, 2018).
In this article, we’ll begin with reviewing timeline estimation techniques and then get into the step-by-step on building an accurate project timeline.
Six Types of Timeline Estimation Techniques
Critical Path Method
For this method, you identify all “mission critical” tasks to complete a project and longest sequence of those tasks you have to take to complete the project. You put pen to paper and map this out into a path, hence the “critical path”. The idea here is if any tasks are delayed, they would delay the entire project, therefore they are deemed critical and placed on the critical path.
Three Point Estimation
This method calculates an expected duration using a weighted average of three estimates: Optimistic, Pessimistic, Most Likely. You would work with your project team to guestimate the three estimates and as a Project Manager, you would complete the formula and provide the weighted average.
Bottom Up Estimation
Many PMs roll their eyes at this one because it takes the longest time to complete, but it has the highest accuracy rate of all methods. You’ll need to work with your team to get extremely detailed on how long each task within a work package will take. Break the work down to the lowest, most specific step-by-step tasks, and then aggregate the time estimates for each step to find your overall duration estimate.
Top Down Estimation
Most PMs opt for top down estimation. You review historical records and predict the timeline for the current project based on past projects. It’s the fastest method but oftentimes the least accurate.
Parametric Estimate
For this method, you would leverage historical data of how long past (similar) projects took and work in other variables such as scope, cost, budget, and duration to get your final estimate.
Expert Judgment
For this method, you would rely on your SMEs to provide their estimate of each work package.
A Step-by-Step Guide to Project Timeline Estimation
Step 1: Work Breakdown Structure + Work Packages
The Work Breakdown Structure, commonly referred to as “the WBS” is a breakdown of project deliverables from your project scope statement. It takes on a hierarchical format, something like the photo below. Your project name sits at the top, with “control accounts”, or high level work, beneath it, and then work packages nest underneath each control account.
For example, perhaps your project is “Labor Day Sale Marketing Campaign”. Your Control Accounts might be “Content Calendar”, “Influencer Marketing”, “Paid Ads”, and “Community Events”. Underneath each of those would be work packages. For Content Calendar you might have a work package for topic research, a separate work package for keyword research, a separate package for putting the calendar together, etc. Each work package should receive a time estimate.
Step 2: Estimate Durations of Work Packages
To create this estimate, you’ll want to leverage subject matter experts. If you’re working on time estimates for your Content Calendar work packages, you may need to pull your content team into a room and discuss how long they think each activity will take. This is where the six different methods of estimating time comes into play.
My recommendation is to use the bottom up estimation technique. You and your SMEs can take every single subtask a work package requires and estimate time for it. For topic research, perhaps you can list out the different channels where you will research, or different brainstorms to host, and then estimate time for each of those activities. Aggregate those time estimates and you have an estimated duration for that work package.
Step 3: Forecast Delays
Leveraging the Critical Path Method and a robust risk management process will be most effective for forecasting project delays. The Critical Path gives you a birds eye view of all the tasks that could potentially delay the project if they don’t go according to plan. It also shows you what tasks are dependent on one another, which increases risk.
Step 4: Create Project Schedule
Once you’ve analyzed your activity sequences (Critical Path Method), work package durations, resource requirements, and schedule constraints (i.e. holidays, team members on multiple projects, etc.), you can begin building your schedule.
If you’re doing this as an agile project, you’ll want to plan your different project release dates and create iterations periods, or sprints, for the team to complete work in.
The project should have a start + end date, as should each activity. Creating a graphical representation of this is best, typically shown as a Gantt chart. Identify project shifts, work days, holidays, team member PTO, etc.
Closing
By following these steps — estimating durations of work packages, forecasting potential delays, and creating a detailed project schedule — you set a solid foundation for your project's success. Leveraging subject matter experts and utilizing effective techniques like bottom-up estimation ensures that your time estimates are realistic and achievable. Incorporating methods such as the Critical Path Method and robust risk management helps in anticipating and mitigating delays, while a well-structured schedule provides clarity and direction for your team.
