Credible Estimation for Small Projects Rita Hadden WDC SPIN February 2001

Where do we Start? n Estimation pre-requisites n Estimation steps n Defining size and complexity for your work n Developing effort estimate for 1 work product n Questions?

Estimation Pre-requisites n An accurate Work Breakdown Structure (WBS) drives reliable size estimates. n Include project management and quality management activities in WBS. n Focus on estimating key deliverables. n If possible, compare with actuals from similar past projects. n Assume your first estimate will be wrong. n Re-estimate at the end of key stages. n Build re-estimation into your WBS.

Estimation Pre-requisites - 2 n Record your estimating assumptions (rationale behind the estimate). n Assign WBS activities to individuals or labor categories. n Assume each task is performed by one person. Adjust for multiple people, or separate the tasks.

Estimation Pre-requisites - 3 n Check your “bottom-up” estimates against “top- down” estimates. n What to ask when two or more estimates are different: – Were requirements different? – Are the assumptions for the two estimates similar? – Are there significant differences in people assigned? – Is the product maturity factor a source of variation?

What To Estimate? n Design n Construction n Documentation n QA/Test n Project Management n Quality Management

When To Estimate? n After Completed Requirements n After Completed High-level Design n After Completed WBS

Estimation Definition Steps (one time) 1. Define size (small, medium, large). 2. Define complexity (simple, moderate, complex). 3. Create 9 categories of size/complexity combinations. 4. Use in-house subject matter experts to develop a “credible” effort estimate for each category.

Estimation Steps for Projects (recurring) 1.Assign each task a size and complexity rating. 2.Use the appropriate standard effort chart to determine the number of hours needed to perform task. 3.Assign “experience factor” and/or “product maturity factor” as appropriate.

Define Size and Complexity for Your Work n 1. Think about what are the unique characteristics of the work you do that affect size and complexity. n 2. Make these characteristics part of your size and complexity definitions. n 3. Find the respected experts in your group for design, code, test, and documentation. n 4. Get their effort estimates for each category based on its size and complexity definition.

Develop effort estimate for 1 work product n 10-Minute Exercise: Pick 1 work product you will be responsible for developing in the next 4 weeks. Estimate the size, complexity, and effort of the work product in 8 minutes or less. Record your rationale (estimating assumptions).

Develop effort estimate for 1 work product n Questions to consider: – What assumptions did you make in order to complete the estimate? – On a scale of 1 to 5, with 5 the highest value, how reliable is your estimate? – What information would you need to estimate more reliably?