Assessment of Prioritization Strategies of the Requirements Gathering

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1 Assessment of Prioritization Strategies of the Requirements Gathering Mohd Shafaat Hussain M. Tech. Scholar, Department of Computer Science and Engineering, Al-Falah School of Engineering and Technology, Dhauj, Faridabad (Haryana), India Abstract Requirements are the basic and most important blocks for the software engineering process. The prioritization of the requirements is also one of the most important task of overall software development process. The Requirement prioritization generally deals with process in which requirements are categorizes on the basis of their importance,software Requirement are also prioritize on the basis to minimize the risk associated with the development process, by this we can implement the high risk requirements first. Requirement prioritization is the most important phase of the requirements management. In Requirement management software requirements for the products are gathered and organized, finally in the release planning activity, these requirements are prioritize and selected for the release. We can say that requirement prioritization is mandatory for software planning. Sometimes the customer is not technical sound and he does not able to differentiate the requirements on the basis of the importance and urgency then project managers must make these decisions on their own.this paper covers the estimation of strategies like Quality Function Deployment,Binary Search Tree (BST),100 point method,moscow method, Cost-Value Approach method of requirement gathering on the basis of various attributes like : Ease of use,accuracy of the result,required number of comparisons and required time to make decisions. Index Terms Requirement Prioritization, Priority Strategies, approaches, assessment, prioritization schemes. I. INTRODUCTION Requirement prioritization in general deals with the reconciliation the business of each requirement against its cost and any significance it has for the architectural foundation [1].Priorities assist to focus on most significant user and customer requirements, If we prioritize the requirements we can easily manage our projects,software development involve many stake holders and they generally have different opinions about requirement's importance and urgency[2],requirements also depend on whether we are working on product or on project [3]. Product does not have identifiable customers and the requirements generally elicited based on the need of some potential users and when one stake holder involve, it is relatively easy to take the decisions, since only one stake holder's decision need to be considered. ershafaat@gmail.com In case of project many stake holders are involve then the decisions to prioritize the requirements are difficult because different stakeholders have different views and opinions regarding the priorities. Based on different stakeholders they have different views about the prioritization for example developers looking for the requirements that can be developed fast, The stakeholder related with the finance department looking for the requirements that generally involve low cost. The stakeholder related with marketing they anticipate for the requirements prioritization on the aspect of requirements with high market value and eventually the customer anticipate for the requirements that he can use easily. Because of the stake holders different opinions there may be a paradox or a contradiction will generate for an example a requirement which can develop easily but have low market value, it will arise point of conflict between the development team and the marketing team, there may be a requirement which is easy to develop but hard to use create a disagreement between the development team and the Customer. So for better prioritization there should be consensus between all the stake holders. Risk is also a major concern to decide the priorities of the requirements, Risk is something that can cause failures, to avoid risk developers try to prioritize requirements which are less vulnerable towards risk. II. STRATEGIES OF PRIORITIZATION Strategies of prioritization[4] generally assign numerical value, alphabets or the symbols that indicate the priority,normally if we use numbers the lower one shows high priority than the one assigned with higher number.the necessary phases the strategies should obey for prioritization (1) Who Prioritize the Requirements(2) Prioritization Guidance (3)Prioritization Goals (4)Prioritization Scales(5)Prioritization Semantics,Who prioritize the Requirements : Prioritization must be done by the collaboration of stakeholders [5](Client, Project Owner, Business Analyst, Project Spencer) because the prioritization must be done after the consensus. Developer and stakeholders must work together as they often have conflicting ideas and views. Lord Krishna College of Engineering (An ISO 9001:2008 Certified Institute) Ghaziabad, Uttar Pradesh, INDIA. Page 254

2 Prioritization Guidance: A common obstacle in front of stakeholders is to choose priorities without any guidance [6], In this scenario most the stakeholder tag most of the requirements as critical and few are important but they are less critical.the analyst assist the stakeholders in prioritization process, The analyst should arise a questionnaire that are what will be the result on the business if the requirements will not include. The analyst ask if there exist any system which will compensate if requirements will not be included.why can t we deferred the requirement to the next phase? What risk is being introduced if a particular requirement cannot be implemented right now? Prioritization Goals: Prioritization is done for two somewhat distinct purposes they are as follows: 1: Defining Scope 2: Scheduling Implementation First of all we are trying to determine which requirements are ought to be the part of the scope and which requirements are out of the scope, the requirements which are within the scope, we need to determine which one is most important than the other one. Prioritization Scales: Effective prioritization needs the use of ranking scales.a number of different scales used to indicate the relative importance of the requirements. We can either use Categorical scale or Numeric scale, Categorical scale have the options such as High, Medium, Low or Critical, Important, Desirable. Priority Semantics: All the stakeholders must be familiar what each priority value mean.for a numerical scale analysis, a small value means low priority while a large value indicates high priority. Similarly for the categorical scale, a definition for each category value needs to be established for an example a priority value HIGH shows a very important requirement without this customer will not accept the product. Medium shows a requirement which is necessary but deferrable, Low or Desirable these are the requirement are of low priority.these above are the attributes which are necessary to choose a method for the Requirements prioritization Now we are going to discuss some of the methods of requirements prioritization and these are as follows. Quality Function Deployment (QFD): Quality Function Deployment (QFD) is a requirement prioritization technique that is used for assuring that quality is built into new processes or system design [7]. It was developed in japan in the mid of 1970s [8].It was later introduced to USA in 1980s. It is a technique for assuring quality is built into new processes. QFD process uses matrices to help the organizations to satisfy their customer s requirements. The first of these matrices is called House of Quality (HOQ). It generally display customer needs and wants along the left side of the matrix and technical requirements to meet these wants are on the top of the matrix. The HOQ has also several sub matrices attached together and they generally relate technical requirements and the technical targets to the customer needs, then a series of matrices generated to address the what with the hows there are several advantage associated with the QFD and they are as follows. It causes product take a less time to reach the market, it causes reduction in design, and it causes increase in the customer satisfaction. The QFD works is as such, first to identify the requirements (external or internal) after that QFD find the technical requirements and eventually use house of quality matrix to relate to customer requirements to the technical requirements. We collect customer requirements by the following steps and they are focused interviews, Surveys, Market studies, Literature, Focus groups, Observation Studies, Benchmark Studies.We collect technical requirements from the inventory elements that are essential for the inventory system. Technical requirements are divided into sub requirements that have several levels. QFD is designed to help the Analysts to focus on characteristics of a new or existing product or service from the viewpoints of market segments, company, or technology-development needs. The technique yields charts and matrices. Binary Search Method of Requirements Prioritization: Another method for sorting elements that is mentioned by Aho.et.al in the year Karlson used this method for the requirement prioritization in the area of ranking requirements [9]. The idea of the karlson to use Binary Search tree is that each node here show the requirement. All the requirements that are placed in the left sub tree of the node are of the less priority, and the requirements that are are on the right sub tree of the node are of high priority. Lord Krishna College of Engineering (An ISO 9001:2008 Certified Institute) Ghaziabad, Uttar Pradesh, INDIA. Page 255

3 When we perform the Binary Search method, first we choose one requirement as the top node, then select one unsorted requirement compare with the requirement at the top of the node, if the requirement is of less priority it will search at the left sub tree, if it will of highest priority then it will search on the right sub tree, this process is going on till no further node remain to be compared and at that time requirement can be inserted into the right position.simple ranking Binary Search method are some of the ways for prioritization of the requirements.simple prioritization is much easier than the bubble sort and the Binary Search method, then the question arises why we use difficult ways of bubble sort and Binary Search Tree method to prioritize the requirements. The answer is quite simple that when we have fairly less amount of requirements to prioritize then simple prioritization is the best way but as the requirements increases people may find cumbersome to remember all the requirements. Since Binary Search Tree is the best algorithms to sort and search information this method can easily employed for the requirement prioritization. 100 points Method or Cumulative Voting Method: 100 points method or cumulative voting [10] is the method of requirement prioritization in which a constant amount given to each stakeholder of imaginary units which he/she can use in voting in the favor most important issues.the amount of money on a particular requirement represent its priority and relative preference from other requirements. The points distributed on the basis of the desires of the stakeholders,each stakeholder has full right to use the amount only on one dominant requirement or use the partial amount.the 100 point method is also sometimes called as proportional voting because the amount assigned to the requirement shows its relative priority over other requirements. Precisely we can say that each requirement occupies certain part of the stakeholder choice. In general 100 points method is the way of spreading the amount of stakeholder freely on the requirements according to his or her choice. In another study [11], 12 requirements were prioritized with the following techniques: CV, MoSCoW and AHP. The results from the study show that CV took longer time than MoSCoW but was faster than AHP. Cumulative voting seems to be a fastest and accurate method, in the recent analysis it is found that cumulative voting is easy to use and take high user confidence.in a study it was found that cumulative voting probably not scale well for large number of requirements.similar analysis has been done by Hutton[]. A similar study conducted by regnell et al. [12] in which the stakeholders prioritize the 58 requirements with imaginary amount of $100,000, this study become the matter of concern because the stakeholders might lose the overview of the requirements if the requirements increases.cumulative Voting also become sensitive if the stakeholders distribute their points based on how they think others will do it to get higher priorities to their favorite requirements MoSCow Method of Requirement Prioritization: MoSCoW is one more successful method for the risk prioritization, Hatton said in [13] that MoSCoW is probably best used in the early stages of projects when requirements are not specified.moscow is the acronym which consist of several words which prioritize the requirements based on the meaning of the words this acronym has In this acronym M stands for Must Have, S stands for Should have if at all possible, C stand for could have if it does not affect anything else, W stands for wont have this time but would like in the future. The two lowercase o are just to complete the acronym. The Must requirement are the compulsory without them project considered to be failure, Must requirements taken into consideration if there will be a consensus between all the stakeholders must check whether requirements matches with the purpose of the project or not. The Should requirements are those that are important but they are not critical they will be positioned second after the Must requirements in the priority list. These requirements are important but their delivery can be postponed for later during the Software development cycle.could requirements are generally nice to have but they are not a necessary factor for the success of the project for an example a fancy user interface.when we include them it will increase the customer satisfaction with the less cost of development, Developers generally try to deliver initially the M, S and C requirements. Lord Krishna College of Engineering (An ISO 9001:2008 Certified Institute) Ghaziabad, Uttar Pradesh, INDIA. Page 256

4 MoSCoW levels of Priority: MoSCoW prioritization is really only meaningful in a specified time, and the same requirement may have different priority at different scenarios.a Must have requirement may not be must have if we consider the project as the whole for example for a computer system the facility to archive the old data is the Must Have requirement, it is very much possible that solution can work properly without this facility for few months without incorporated it in the project, so it is very much sensible to make archive facility a Should or Could for the first phase even though it will become Must Have before the end of the project The Requirement Engineers apply AHP pairwise comparison to estimate the relative values of the requirements. The Engineer Use AHP to calculate the relative value and the cost attach with the requirement and then plots these on the Cost Value diagram. Cost-Value diagram use to estimates the relative cost and value of the requirements. The Cost-Value approach [16] is one example of prioritization methods. It presents requirements by the help of cost-value diagram. Both cost and value for each requirement are computed with the AHP technique. Each piece of project has its priority, so we have to assign priority before the project begin and kept under continuous search till the work is done. Priorities may change with the introduction of new requirements or the unexpected work arises with the current requirements, the decision must be made how much critical they are with the current work using the MoSCoW rules. Cost-Value Approach of the requirement Prioritization: Cost Value approach [14] is relatively a best and easy way to priorities the requirements in term of the cost involve in a particular requirement and the the value a requirement has. The analysis of the cost and the value was performed by using another method called as Analytic Hierarchy Process (AHP), This method was created by Thomas Saaty [15].Its basic idea is that for all pairs of (candidate) requirements a person assesses a value or a cost comparing the one requirement of a pair with the other, for example a value 4 for the pair of requirements (Req1, Req2) it shows that Requirement1 is valued four times to the Requirement 2. This indicates that (Req2, Req1) has value ¼.. For the Cost-Value approach following steps should be consider and they are as follows: The Engineers related with requirement phase review requirements for the completeness they ensure that requirement stated precisely III. COMPARISON OF THE PRIORITIZATION OF THE TECHNIQUES The comparison of various techniques depends on the following factors that is how easy to apply a prioritization technique [17] how best it is in comparison with other techniques. The comparison below is on the basis of how the particular technique is best suited for the requirement prioritization [18] Simpler to Use 0 QFD BST CV MoSCoW Cost-Value Prioritization Strategies Rank vs. Prioritization techniques The above figure shows the rank of the strategies of prioritization based on the simpler to use as precisely shown by the figure the BST (Binary Search Tree) method is much easier than its counterparts, after that CV (Cumulative Voting) comes into the picture and then QFD (Quality Function Deployment). The second attribute to decide which method is best for prioritization is the estimated time taken by the strategy to complete the prioritization. Lord Krishna College of Engineering (An ISO 9001:2008 Certified Institute) Ghaziabad, Uttar Pradesh, INDIA. Page 257

5 QFD BST CV MoSCoW Cost-Value PRIORITIZATION STRATEGIES Time vs. Prioritization techniques The above figure shows that how much time a prioritization technique take to prioritize the requirements, from the figure above it was concluded that while prioritize the relation from the above figure it is inferred that CV (Cumulative voting ) take less duration than other strategies, after that BST takes less duration to complete the prioritization, and then Cost-Value Method is the strategy takes less time to prioritize the requirements.the third attribute is that which method will do best with large number of the requirements. 8 Adaptability QFD BST CV MoSCoW Cost-Value The figure above is the Rank vs. Adaptability of the strategy From the above comparison we found that CV has the lowest rank after that cost value approach and then QFD is the best strategies. IV. CONCLUSION In this Research paper we have analyzed five requirements strategies 1. Quality Function deployment (QFD) 2. Binary Search Tree (BST) 3. Cumulative Voting 4. MoSCow 4.Cost-Value approach and eventually the consequences reach a consensus that surely CV Cumulative Voting is the best strategy which is quite useful if we want to prioritize the requirements. "Sharpening Skills... The analytical comparisons above has shown several relative performance of strategies when we try to prioritize the requirements, from the above comparisons it has come that Cumulative Voting is a simpler strategy to use, it takes less time taken to prioritize the requirements and if there are more requirements are present to prioritize then it is much better than its counterparts. However if we see when we compare the strategies on the basis of the duration BST (Binary Search Tree) is much better than this and it is as equivalent to the Cost-Value approach when we compare on the basis that which approach is much suited if there are more requirements to prioritize, but eventually if we see all the comparisons collectively the cumulative voting is much better choice than its counterparts. If we look on the other strategies like QFD (Quality Function Deployment) although it is best suited from BST and MoSCoW if we compare the prioritization techniques based on adaptability but overall it is not a best choice.similarly if we talk about BST it is much suited technique than CV if we talk in terms of time, but in other comparison CV is a better choice than BST (Binary Search Tree). REFERENCES [1] Rupp C. Requirements and Psychology. May/June 2002 [2] H. F. Hofmann and F. Lehner, Requirements engineering as a success factor in software projects, [3] X. Liu, Y. Sun, C. S. Veera, Y. Kyoya, and K. Noguchi, Priority assessment of software process requirements from multiple perspectives, Journal of Systems and Software, vol. 79, no. 11, pp , 2006 [4] P. Berander, K. Khan, and L. Lehtola, Towards a research framework on requirements prioritization, in SERPS06: Sixth Conference on Software Engineering Research and Practice in Sweden, 2006, pp [5] DeMarco, T. and Lister, T. (1987) Peopleware: productive projects and teams, Dorset House Publishing, New York. [6] K. E. Wiegers, First things first: prioritizing requirements, Software Development Magazine, vol. 7, no. 9, pp , [7] Associates Inc. [3] Robin Rawlings-Quinn, QUALITY FUNCTION DEPLOYMENT (QFD): A CASE STUDY. [8] Akao, Yoji (1994). "Development History of Quality Function Deployment". The Customer Driven Approach to Quality Planning and Deployment. Minato, Tokyo 107 Japan: Asian Productivity Organization. [9] T. Standish, Data Structures in Java, Addison-Wesley, Boston, USA, [10] P. Berander and P. J onsson, Hierarchical cumulative voting (hcv) prioritization of requirements in hierarchies, International Journal of Software Engineering & Knowledge Engineering, vol. 16, pp , Lord Krishna College of Engineering (An ISO 9001:2008 Certified Institute) Ghaziabad, Uttar Pradesh, INDIA. Page 258

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