Estimating Task Work and Duration
Estimating the work effort is the topic of the third article in a series on estimating resources for an electronic health record (EHR) project. The first article, Introduction, describes the basis for these discussions as well as the series to follow. The second article, Defining Resources, discusses how to create the tasks and designate the resource roles assigned to the task in the Resource Assignment Matrix (RAM). The third article will show how to use the RAM created in article two and add work, duration and resources to the tasks.
Let's take a look at how to use your RAM to add work and duration for each task. The RAM (Appendix 1) lists all the tasks and resources needed to complete the tasks. The tasks from the RAM should be copied into a project management software application, such as Microsoft Project (Appendix 2). An additional tool to assist with estimating duration is a risk register (Appendix 3) which contains the identified risks. A risk is a positive or negative event that may impact the ability to meet the project objective. For example, if a particular task has a high risk probability then the duration or work for that task may need to be increased.
We will focus on three task duration and work estimating techniques: expert judgment, analogous estimating, and three-point estimating. Expert judgment is generally used when no historical data is available from past projects and involves requesting individual team members to provide work and duration estimates. The second estimation technique, analogous estimating, uses historical information as the source for estimating duration and work. The last estimation technique, three-point estimating, involves gathering three time frame estimates for each task: most likely, optimistic, and pessimistic.
The next step is to combine all three estimates to come up with one single value. The most common method of obtaining an accurate single estimate is by using the Program Evaluation and Review Technique (PERT). PERT uses a formula in Microsoft Project that places an emphasis on the most likely estimate but still takes into account the pessimistic and optimistic estimates (Appendix 4). Microsoft Project only supports estimating duration with PERT. However, you may create an Excel spreadsheet and average the likeliest, optimistic and pessimistic work estimates. Then enter that value into the work column in Microsoft Project. Three point estimates will be more accurate than single point estimation. This is recommended for estimating work or duration for tasks without expert judgment or historical performance baselines.
The next step is to attach the resources to your tasks. In order to complete this step the resource sheet in Microsoft Project must be populated from the resource names in the RAM (Appendix 5). Once the resource names are transferred to the resource sheet, attaching the resource to a task is easy. From the Gantt view, click the cell below “Resource Name” and the list of resources from the resource sheet will present. Select a resource name and that person(s) will be assigned to the task (Appendix 6).
At this point in the process, the RAM has been used to populate both the tasks and the resource sheet within Microsoft Project. Three estimating techniques for work and duration have been discussed and resources have been assigned to tasks. The fourth article in this series will discuss resource calendar and task relationships to finalize the EHR project schedule.
Appendix 1 – Resource Assignment Matrix (RAM)
Appendix 2 – Copy tasks from RAM into Microsoft Project and add Resources
Appendix 3 – Risk Register
Appendix 4: Adding the PERT Analysis Toolbar
Appendix 4a: PERT Analysis View
Appendix 4b: PERT Analysis with duration estimates
Appendix 5: Populating Resource Sheet in Microsoft Project
Appendix 6: Assigning resources to a task in Microsoft Project