By Majesh reddy Salla

Introduction Factors for poor estimation Agile Process Agile effort estimation techniques Planning poker Analogy & Expert opinion COSMIC method Effort predictors Effort estimation on planning levels Estimation accuracy Agile methods Survey results conclusion

Effort estimation: A software development process in which we predict the amount of effort required to develop and maintain software. Software effort estimation is a crucial activity in software development. Estimates are the key input to project resource allocation and duration. It is important to use the correct estimation technique to avoid issues caused by poor estimation.

Lack of estimating experience. Lack of historical data on which base estimates. Lack of systematic estimation process, techniques or models suited to project needs. Unrealistic expectations or assumptions. Failure to recognize and address the uncertainty inherent in project estimates.

In agile processes, software development is iterative process where the product is developed and working pieces are delivered to customers. In this development process there are three phases of planning or estimation. They are Iterative planning Release planning Daily planning

There are different types of estimation techniques that are used for agile development process. Planning poker Analogy Expert judgement

Planning poker is widely used. Among 60 agile practitioners surveyed, 63% of them uses planning poker technique. Planning poker approach Individual stories are presented for estimation After a period of discussion each person chooses a numbered card from his deck to give the effort estimation. All estimates are kept private until every one chooses Finally all estimates are revealed and again discussion starts..

Expert opinion seeks help of experts to estimate the work. They estimate based on the what companies are experiencing in industry. Analogy finds similar projects to the project that need to be estimated. Based on the data from old projects they estimate the current project. All these techniques can be used by themselves or combined.

All the previous techniques use subjective assessment. To improve the accuracy of the effort estimation, there is COSMIC method approach, based on constructive cost model. User stories are represented as functional requirements. Functional requirements are known as COSMIC function points (CFP). Used to calculate the effort per CFP.

Size metrics and cost drivers are effort predictors. Story points, use case points and functional points all are used as size metrics. The mostly used one is story points. Teams expertise level and teams experience are mainly considered as cost drivers for agile methods. Task size, project domain and non-functional requirements are also cost drivers.

Web based questionnaire hosted at surveymonkey.com Done between August and October of Collected data from the agile practitioners across the world from 16 different countries. Survey Questions Which effort estimation technique? What agile development activities? Effort estimation compared to actual effort? (accuracy)

Effort estimation can be done in three planning levels. In the survey, practitioners estimated the effort mostly in iterative planning and release planning. Daily planning effort estimation is done very less when compared to iterative and release planning. As per the survey effort estimation plays a pivot role in release and sprint planning.

Estimation accuracy refers to the amount of estimation error (actual effort – estimated effort). Very few had less than 5% of error among estimation techniques that are used. Most of them were over/underestimated effort. Tendency of underestimated development could be attributed to over optimism and team members inexperience.

Most of the effort estimation techniques were performed on two models. Extreme programming Scrum model The fact that study didn’t consider other agile methods which makes it hard to determine how accurate estimations be in other models

63% of the practitioners use planning poker estimation technique (analogy-47% and expert opinion-38%) 62% of them used story points as size metric. Teams expertise and experience are common cost drivers. 52% of the respondents believe that their effort estimates on average are under/over estimate by an error of 25% or more. Most estimation takes into consideration implementation and testing activities. Estimation is mostly done at sprint and release planning levels.

Described several effort estimation techniques that are used in agile processes. The effort predictors, planning level at which effort estimation is done a lot, estimation accuracy, activities considered during estimation and agile model are the factors that will be helpful in determining the estimation is a good estimate or not. There is no particular standard technique for effort estimation in agile models.

* 1 ) Carlos Eduardo Lima Peixoto., Jorge Luis Nicolas Audy., Rafael Prikladnicki., “The importance of the use of an estimation process”, Proceedings of the 2010 ICSE Workshop on Software Development Governance, PP , Association for Computing Machinery (ACM) New York, USA. * 2)Jean-Marc Desharnais., Luigi Buglione., Bugra Kocaturk., “Using the COSMIC method to estimate Agile user stories”, Proceedings of the 12th International Conference on Product Focused Software Development and Process Improvement, 2011, PP , Association for Computing Machinery (ACM) New York, USA. * 3)Muhammad Usman., Emilia Mendes., Francila Weidt., Ricardo Britto., “Effort estimation in agile software development: a systematic literature review”, Proceedings of the 10th International Conference on Predictive Models in Software Engineering, 2014, PP , Association for Computing Machinery (ACM) New York, USA. * 4)Muhammad Usman., Emilia Mendes., Jurgen Brostler., “Effort estimation in agile software development: a survey on the state of practice”, Proceedings of the 19th International Conference on Evolution and Assessment in Software Engineering, 2015, Article No. 12, Association for Computing Machinery (ACM), New York, USA. * 5)Valentina Lenarduzzi., “Could social factors influence the effort software estimation?”, Proceedings of the 7th International Workshop on Social Software Engineering (SSE), 2015, PP , Association for Computing Machinery (ACM) New York, USA.