The Book about Cost Estimation in Agile Software Development

Agile software development and a binding agreed delivery date are not mutually exclusive at all. On the contrary, the principles of the Agile Manifesto are well-proven measures to mitigate the typical risks of development projects with binding regulations.

Crucial for the achievement of project goals is a reliable plan which can be created without significant expense and readjusted flexibly in case of changed requirements. Under these conditions, indirect cost estimations on basis of functional size measurements are a proven practice. They require the size of the functional requirements as an input value, determined by precise rules, as well as an empirical value of the own productivity, measured after earlier sprints.

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For the determination of functional size, methodological knowledge and expertise is required regarding the selected method, for example Function Point, COSMIC or Data Interaction Point method, along with a sufficient specification of requirements, for example by described use cases and elementary processes. Under these conditions, the resulting value is a valid key figure of the functional requirements’ size. It is independent from the individual performing the estimation. Repeated estimations of the same requirements always result in the same value.

An empirical value of the own productivity, that is the functional size which can be typically implemented by the team with given personnel costs, is required in addi-tion. It can be measured and updated within the scope of regular retrospectives of completed increments, sprints or releases. Thereby, the implemented functional size is set in relation to the arising personnel costs. The functional size is determined by counting – depending on the method – elementary processes or data elements. With an appropriate mapping to structural characteristics of the system, this counting process can be automated. A such counting program, once implemented, can quickly measure the total size of the system and, by comparing the current size with the previous measurement, return the growth of the functional size resulting from the last development process. 

Regularly measured and compared values of productivity and quality - in the simplest case the number of production defects – aid in recognizing any need for action and allow to verify the effectivity of implemented improvement measures.

This book illustrates, how size metrics can be utilised profitably in software development processes oriented towards agile values. It points out differences and restrictions, how the accuracy of cost estimations can be increased with each sprint and examines the feasibility of automated measurements. It is available as eBook, paperback and hardcover at most bookshops, for example at Amazon.com.