The estimating of software development is both straightforward and complex. When it is suggested that estimating is hard, of no value, and unnecessary, always ask what principle is used to support that claim? Don't hear one? Then it's likely just a personal anecdote made without any principles.
Here are some resources that will provide guidance to produce credible software development estimates, in both traditional and agile domains.
Let's start with some books. While some have publication dates that may seem old, the principles in these books are immutable, even for agile projects.
- Software Sizing, Estimation, and Risk Management: When Performance is Measured Performance Improves, Daniel Galaorath and Michael Evans, Auerbach, 2006.
- Software Sizing and Estimating: Mk II FPA, Charles Symons, John Wiley & Sons, 1991.
- Agile Estimating and Planning, Mike Cohn, Prentice Hall, 2006.
- Estimating Software Costs: Bringing Realism to Estimating, Second Edition, Capers Jones, 2007
- Software Engineering and Metrics, Conte, Dunsmore, and Shen, 1985 - this is the book where the favorite quote of #Noestimaytes advocates, where they misquote the numbers and the math. See "estimating accuracy mathematics" for the actual mathematics.
- Software Estimation: Demystifying the Black Art, Steve McConnell, Microsoft Press, 2015.
- Software Metrics: A Rigorous and Practical Approach, Thord Edition, Norma Fenton and James Bieman
- Estimating Software-Intensive Systems: Projects, Products, and Processes, Richard Stutzke, Addison-Wesley, 2005.
- Software Cost Estimation with COCOMO II, Barry Boehm, et. al., Prentice Hall, 2000.
- Practices for Scaling Lean & Agile Development: Large, Multisite, and Offshore Product Development with Large-Scale Scrum, Craig Larman and Bas Vodde, Addison Wesley, 2010.
- Scaling Lean & Agle Development: Thinking and Organizational Tools for Large-Scale Scrum, Craig Larman and Bas Voode, Addison Wesley, 2008.
- Agile Project Management: Creating Innovative Products, Jim Highsmith, Addison Wesley, 2004.
- Forecasting and Simulating Software Development Projects: Effective Modeling of Kanban & Scrum Projects using Monte-Carlo Simulation, Troy Magennis, Focused Objectives, 2011.
- How Many Licks: or how to estimate damn near anything, Aaron Santos, Running Press, 2009
Here's a set of papers (being added to often) for estimating agile software development projects
With the books and papers, you'll now have the basis to develop yor own