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The theory of corporate information systems

Abstract: the article is devoted to the proposal of a new way to build a resource plan for ERP-system implementation projects, which has ease of use and speed of obtaining results, and this in turn allows you to flexibly emulate various situations. The method is applicable to corporate system implementation projects in which the software development is carried out. The proposed method uses the mechanism of the RICEF estimator, which is an expert assessment of the labor costs for preparing and developing programs for a pair of parameters «type of development – complexity». In the future, benchmarking is used, which determines the duration of the project phases in percentage terms. Based on the calculated efforts that define the stages of design and build, and the results of benchmarking, the timing of all remaining phases is calculated. The distribution of labor costs for the remaining stages of the project is carried out according to the pyramid principle, for which milestones of the analysis, integration testing and cutover are processed. The final plan of human resources is based on the calculated labor costs set for all stages of the project. Consequently, creation of the project schedule, determination of the scope of work for all phases, as well as finalization of the resource plan are carried out using only the planned labor costs of design and build stages.
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1. Introduction

Having decided to link your life with a career as a consultant of corporate information systems implementation (hereinafter – ERP systems) [1], it does not matter American, German or Russian production, there may be a mistaken feeling that you should certainly be able to program and only your technical skills play a role. This is not quite true. The beginning of corporate information system implementation projects, which seems to be a very non-trivial task, is always preceded by a fairly large number of work, which is indirectly related to technology [2]. From the project management point of view, the beginning of the ERP-system implementation is almost final and fairly predictable activity. The stages of analysis, design, build, testing, cutover, as well as post go-live support are typical of the project of implementing corporate systems (Fig. 1). Usually, the analysis stage is preceded by the activity of creating a technical task justifying the feasibility of implementing an ERP-system, as well as the key requirements for it, which beginners may not know due to lack of experience [3]. Next, technical and commercial proposals are formed, which describe what stages the project will consist of, the duration of the stages, the amount of necessary human resources, as well as how the requirements will be covered [4]. The contract for the implementation of an ERP-system is concluded only in case of successful sales, followed by just those six stages of the project that we have described above.

 Fig. 1. Typical six stages of corporate information system implementation projects 

2.    Problem Statement

Building a resource plan is an important issue in the preparation of technical and commercial proposals, it determines the necessary amount of human resources for the project. Project timeline, the amount of human resources, as well as the composition of the expected work are closely related, which can be set by the following simplified formula:

Project duration = Total efforts / Number of human resources.                (1)

The preparation of resource plan should be carried out in accordance with the content of the project, since changing the content will lead to an adjustment of the duration, which is easy to see in (1). A natural question arises, how to build a resource plan? The project management body of knowledge (hereinafter – PMBoK) talks about critical path and chain methods that allow you to build a logical structure of the work performed, set their duration, assign human resources for tasks and fix time buffers [5]. PMBoK describes project work «from the bottom up», that is, the final value is the sum of many individual subtasks. The necessary amount of resources is determined by calculation of the duration and scope of work in (1), after which they are aligned and smoothed in accordance with the stages of the project. Both methods are time-consuming and, of course, not flexible, but do not require deep technical knowledge. The created project plan is not of great value, the value lies in its daily adaptation to the prevailing realities, it is idea that can be found in the work [6], devoted to Agile planning. Really, the method should perform calculations quickly in order to provide modeling of a variety of possible situations, one cannot disagree with it. In practice, the application of the methods described both in [5] and in other literary sources similar in content [7-9], which provide a general understanding of building a resource plan, is very laborious and problematic. The purpose of this paper is to propose a faster way of building a resource plan for ERP projects. Achieving the goal requires consideration of the following tasks:

  • overview of ways to evaluate efforts for program development;
  • analysis of the duration of stages for ERP-system implementation projects;
  • quick creation of a resource plan for ERP projects.

3.    Evaluation of Development Efforts

From the formula (1) it is easy to conclude that finding the number of human resources requires determining the timeline of the project and the amount of work performed. Let's rephrase: it means building a resource plan requires calculating the duration, as well as the labor costs of each stage of the project. Usually, the customer provides a potential contractor with a technical task even before the start of the ERP-system implementation project, which specifies a list of the user's initial requirements for the future information system. Each of the requirements is analyzed by the contractor's experts to be classified as Fit or Gap [10-11], which is a mandatory step for preparing a preliminary ERP project plan. The requirements from the Fit area are considered already implemented by default in the basic package of ERP-system and do not require additional efforts, on the contrary, the Gap area serves as a signal about the need to refine or configure the information system (Fig. 2).

Fig. 2. Fit/Gap-analysis schema  

The type of development and complexity are determined for each Gap requirement. RICEF classification is used for it, where R is report, I – interface, C – dataprocessing program (i.e. convention), E – anextension of the standard functionality of ERP-system (i.e. enhancement) and F – printedform. The complexity of the development is characterized by such values as: low, medium, high, very high [12]. The matching of the two parameters «type of development – complexity» is performed for each Gap requirement. The contractor's company has efforts determined by experts, necessary for the preparation of project documentation and the development of a program for all possible values of these pairs. Thus, RICEF estimator (Fig. 3) is a matrix linking the type of development and its complexity, as well as the planned efforts to prepare technical documentation and software development.

Fig. 3. Fragment of a RICEF estimator  

4.    Benchmarking of the Stage Durations

Stages allow you to group the same type of project tasks into a logical sequence of work. In fact, the stages of corporate systems implementation are a set of phases inherited from the software development lifecycle, from which the stages of idea and termination are excluded. The content, quantity, and the name of the phases strongly depend on the type of ERP project, in particular, they are distinguished:

  • implementation «from the scratch», including pilot projects;
  • rollout;
  • development.

If we summarize the knowledge in the field of ERP-systems implementation, then the typical stages, regardless of the project, will be those given in Fig. 1. Of course, the specifics of projects dictate their own features, for example, pilot projects often include a pilot operation stage, but this does not significantly change the course of the project, so the typical six stages remain virtually unchanged.

Literature sources devoted to ERP projects [1-4], unfortunately, give only a general estimate of the duration of such projects. The implementation of ERP-systems from one year or more is considered the norm, but it is problematic to find more detailed information on the duration of each phase. Therefore, as statistical information, we will use the Russian projects mentioned in [13-14]. And based on them, we will try to formulate the recommended duration of the stages. This information is very important to us, without it we will not be able to build a human resource plan.

The RICEF estimator provides the calculation of efforts at the design and build stages. However, the duration of these two stages remains unknown. Let's take a closer look at all stages of ERP-system implementation projects. Statistics show that the sum of the design and build stages is at least 50% of the duration of the entire ERP project. Post go-live support stage is not included in the evaluation, since its duration is a constant agreed with the customer. Then it is possible to calculate the duration of all stages of the project in percentage terms using proposed benchmarking mechanism (Fig. 4).

Fig. 4. Benchmarking of the stage durations for ERP-system implementation projects in percentage terms, as well as the approximate duration of the phases for a typical case 

So, the duration of the design and build stages is half of the project, and their percentage also varies. Usually the build stage lasts at least one and a half times longer than the design stage. The durations of the design and testing stages are comparable. The cutover stage is the shortest. Thus, you can find out the duration of the entire project by calculating the duration of at least one of the stages. The existing efforts for the preparation of project documentation and the development of programs calculated upon RICEF estimator will help us in this. 

5.    Building a Resource Plan

And now we will propose an algorithm for building a resource plan, knowing the efforts, as well as the preliminary duration of the stages of the ERP project. In our example, we will use the labor costs of the design and build stages, calculated based on the RICEF estimator, equal to 113 and 163 man-days, respectively. Then the procedure for building a resource plan will be as follows:

  • it is required to set the initial duration of the design stage, considering the data in Fig. 4;
  • then we impose the efforts of functional consultants found by RICEF estimator on the calendar grid. If the amount of labor costs exceeds the duration of the phase, you should add an additional human resource.The duration of the design stage and overall efforts of the functional consultants should coincide or differ by a minimum amount. Since calculation of the number of resources depends on the duration of the stage, we are guided by the rule that this number should be minimal. If it is not possible to select multiple resources, it is allowed to change the initial duration of the phase in greater or lesser directions.Selecting the optimal ratio of the phase duration and resource allocation, we find their final values;
  • found duration of the design stage, equal in our example to 36 working days, allows us to find the duration of the entire project using a percentage of the benchmarking results (Fig. 4);
  •  we determine the number of developers, the same procedure is used as described in step 2, with the only exception that timing of the build stage has already been found on step 3;
  • we will distribute the found number of consultants and developers to the remaining stages of the project, but exclude the analysis stage for developers, since they are not involved in it. We get a preliminary resource plan containing the total amount of effort in 1038 man-days (Fig. 5A).

Using the proposed procedure, we were able to build a resource plan for the corporate system implementation projects from the start date of the project. In this case, there is no limitation on the duration of the project. If the customer explicitly fixes the start and end dates of the project, the proposed scheme is also working, but you will need to reduce the duration of the design phase already at the 1ststep. After calculating the duration of all phases of the project, i.e. the duration of the entire project, it is compared with the start and end dates set by the customer. If necessary, the procedure is repeated many times, until the values of the phase durations satisfying the requirements are found. It is important to emphasize that the shorter project timeline, the more resources will be involved. The latter generates more likely risks of failure compared to a project of longer duration, but with less involvement of human resources.

The example of the plan in Fig. 5A seems redundant, in particular: the participation of not all functional consultants and developers is necessary at all stages of the project.

There is a hypothesis saying that the maximum amount of resources is required at the most critical stages of the project. In some literary sources [10, 15], this statement is called the pyramid principle. For us, these are the design, build and testing phases. Then we are able to propose the formula (2): 

Number of resources at current stage =

RoundToInt (Number of resources at previous or subsequent stage / 2),       (2)

which will reduce the number of people in functional groups, considering the number of resources involved in the previous or subsequent stages. The assessment is empirical in nature, based on such project activities as: analysis, integration testing and technical cutover.

We can apply (2) and clarify the number of

  • consultant resources at the analysis stage regarding the design phase;
  • consultants at post go-live support stage regarding the cutover phase;


  • developers in the acceptance testing, cutover, and post go-live support phases regarding to the build stage.

Fig. 5.  Example of the human resources: a)       preliminary redundant plan; b) final shortened plan  

As a result, the volume of labor costs decreased by 15% and amounted to 887 man-days (Fig. 5B). Thus, it was possible to significantly reduce the involvement of team members in the ERP-system implementation project. The resource plan is based on a number of assumptions, in particular: ideal man-days are used to calculate the efforts, qualified personnel are considered, and projects of the corporate information systems implementation are processed, requiring only the development. Ideal man-days imply a situation where a person spends 100% of his time working without being distracted by any other tasks. According to [16], the best indicator of person employment is 70% of the working time, for example, at Toyota, at all other enterprises this indicator is noticeably worse. The amount of resources in the plan depends on the qualifications of employees, so the calculation is mainly carried out for human resources with more than five years of experience. In the case of using resources with lower qualifications, a recalculation of the plan will be required, which will lead to its increase. The resource plan is formed on the basis of two parameters: the scope of design and development work, which is its current limitation. However, in real projects, the number of tasks is much larger, for example, if we follow the theory of corporate systems [17], then a typical project has more than eleven groups of tasks. 

6.    Conclusions

So, what was the reason for writing this article? The analysis of literary sources [5-6] showed that at the moment there is no universal method for quickly creating a resource plan in projects for the implementation of corporate information systems. The available methods based on the critical path and chain oblige us to choose the duration of each task already at the initial stages of building a resource plan, which is incorrect, since the duration of the project is the value that we must find in the end. According to the author, the creation of a resource plan is reduced to the construction of a project schedule, in which the calculation of the stage durations and the resources involved is represented by two completely different, but interdependent tasks. The number of human resources affects the timing of the project and, conversely, the timing should be set based on the number of resources. The solution of this dual problem is the basis of the method proposed by the author.

The article proposes a method for quick creation of a resource plan for ERP-system implementation projects, for which the planned labor costs for the preparation of documentation at the design stage, as well as the development of programs at the build stage are used as input parameters. Labor costs at the design and build stages are determined using the RICEF estimator, while benchmarking allows you to determine the duration of all remaining stages of the project, knowing the timing of the design phase. Thus, the method is two-parametric. The proposed method ensures the creation of a human resources plan from the start date of the project. To form a plan from the end date of the project, it is necessary to shorten the duration of the design stage and increase the number of its human resources. At the same time, it should be taken into account that the shorter duration of the phase, the higher risks of non-fulfillment of tasks, regardless of the increase in the number of resources [18].

 Fig. 6. Parameters determining the content of ERP-system implementation projects according to the theory of corporate information systems 

Further development of the method consists in refining and automating the algorithm for reducing resources (2), as well as including actions not related to design and build in the scope of calculation. In the first case, you can apply the concept of entropy from information theory [19], in the second, you should use the theory of corporate information systems [17], which will determine an additional set of parameters responsible for the content of the project, namely: data migration, business cutover, roles and authorization, as well as change management (Fig. 6). Other parameters shown in Fig. 6, have already been included in the two-parameters method. The use of extra parameters will make it possible to transform the method of constructing a resource plan into a more complex algorithm, in which a larger number of project tasks will be taken into consideration.


Implementation of corporate information systems, in particular, ERP-systems, is carried out mainly with the use of preconfigured software solutions from various vendors. Examples of such program solutions are integrated applications SAP ERP, Oracle eBS, Microsoft Dynamics NAV and 1C ERP. The use of approved software products allows you to reduce efforts during implementation, however the problems of application customization and build are still open [1]. The focus on digitalization of private and public sectors dictates special requirements for company’s maturity and hence technological and innovative nature of the enterprise, which is impossible to imagine without using modern software systems. The topics of artificial intelligence, machine learning, the internet of things and cloud solutions are reflected in corporate information systems, which makes it necessary to significantly rethink the approach to planning and implementing software systems.

Realization of all information systems is based on several classical implementation models. Nowadays the most popular are applied methods based on the Agile methodology. The Agile methodology allows you to look at the task of programming complex software solutions differently, despite all project uncertainties. If you carefully read the literature on the Agile methods [2-3], you will misunderstand that this is a panacea for everything, especially in comparison with the classic development methods. Is this really the case? We will try to find an answer to this question in the current article.

2. Problem statement

The purpose if this paper is to demonstrate the usage of the cascade, iterative and spiral models in ERP-systems implementation projects under business and technological uncertainty. The following tasks will be considered to achieve the goal:

  • consider waterfall, iterative and spiral implementation models;
  • define business and technological uncertainty in ERP-systems implementation projects;
  • explore basic principles of developing complex software programs in ERP-systems;
  • analyze business uncertainty in cascade and multi-pass implementation models;
  • refine the usage of implementation models in ERP-projects.

3. ERP-system implementation methods

There are three classic models of developing software programs regardless of their complexity and business orientation. The waterfall, iterative and spiral models were proposed more than forty years ago and are applicable to implement ERP-systems [4]. All other methods are derived from them (V-model, Scrum, Kanban and many others). It is important to say that previously by implementation of information systems mainly meant development of an application from scratch and configuration played unimportant role. Now the rules of the game have changed: corporate information system is considered as a customized software solution which can be rebuilt. Thus, project of implementation modern ERP-systems is about proper configuration and modification of the package solution. Statistics on the use of foreign ERP-systems from SAP, Oracle and Microsoft companies in Russian enterprises indicate following [5]: 30% of business requirements are covered by ERP-system configuration, 60% of requirements need system modification and remaining 10% are distributed between first two points, depending on the company’s industry specifics.

The cascade or waterfall model was proposed in 1970. The implementation project according to this model requires completion of all tasks at the stage, transition to the next stage is possible only if previous ones are successfully completed. It is forbidden to skip the stages, go back to the previous ones and repeat them. The ERP-system implementation project based on this model consists of the following activities:

  • project preparation;
  • identification, detailing and prioritization of requirements;
  • paring designs and functional specifications;
  • customization aprend development of software system;
  • performing unit, integration and user acceptance tests;
  • data migration and end user training;
  • go-live and post go-live support.

The model is used in implementation projects of ERP-systems, integrated with a variety of third-party subsystems, where even the most minor amendments in requirements lead changes in the project time, scope and costs. Due to this, the waterfall model is often used in «from scratch» and «rollout» implementation projects characterized by quite a lot of effort. The main weak point of the model is that there is no feedback loop between project stages. Therefore, errors made during ERP-system conceptual design are detected only during user acceptance test, when it is impossible to make significant changes to the program code. Examples of the waterfall model are implementation methodologies such as ASAP (Accelerated SAP) from SAP AG, MDSS (Microsoft Dynamics Sure Steps) from Microsoft and AIM (Application Implementation Method) as part of Oracle Unified Method concept [6].

A distinctive feature of the iterative model is providing a feedback between the project stages, returning to previous stages as well as multiple stages. The model was proposed in 1957. The development process is reduced to a series of fast, independent and adaptive iterations that rapidly bring semi-ready software solution [7]. Each iteration ends with a demonstration of the intermediate product to the customer for quick gathering comments and error detection. During iterations the understanding of final software product may change, so it is allowed and encouraged to add new requirements. The duration of each iteration varies between 1-4 weeks, and the number of iterations is calculated based on the end date of the project or budget. The ERP-system implementation project according to the iterative model consists of the following steps:

  • identification, detailing and prioritization of business requirements;
  • calculation of number and duration of development iterations;
  • realization of a part of ERP-system, functional and integration testing, followed by demonstration of semi-finished software product to the customer in order to clarify requirements to be implemented in further iterations of development, transfer of the software solution to the productive environment (for each iteration of development) ;
  • user acceptance test;
  • migration of master and transactional data, end user training;
  • go-live and support.

As you can see from the above list, there is no design and documentation of the solution, this is indeed the case. However, since post go-live support ends up transferring the software system to customer support, in practice, documentation still has to be prepared. In comparison with the waterfall model, the iterative scheme is used in evolution projects where requirements can be formulated only superficially by end users. The increase in efforts, the use of expert evaluation and rough criteria to complete the project are the main disadvantages of the iterative model.

The spiral implementation model was proposed in 1986 and combines both a waterfall and an iterative approach. The focus of this model is on risk assessment and decision-making readiness. The spiral model is often considered as a special case of the iterative model, each cycle of development of this model is comparable to iteration and is characterized by:

  • definition of goals and objectives;
  • qualitative and quantitative risk management;
  • modification and testing of solution;
  • evaluation of the results and planning of the next round of development.

The ERP-system implementation projects based on the spiral model are similar to the iterative scheme with the only difference that each round of development, in addition to risk management, includes:

  • assessment of a need for the next round of development;
  • assessment of understanding of system requirements;
  • analysis of the feasibility to complete the project.

Managing deadlines, resources, budget, quality, communications and other project parameters, as well as assessing the need to complete the next development rounds require a lot of effort. The model is applied in projects for the evolution of ERP-systems [8]. For small subprojects, time spent on processing and evaluating the project parameters will exceed the time needed to finalize the software system itself.

Iterative and spiral models are often called multi-pass models, the waterfall scheme is called one-pass model. As mentioned above, iterative and spiral models have eliminated main drawback of the cascade scheme: lack of a feedback loop, which does not allow to correct errors from previous stages in time. The formalization of the principles providing feedback loop is reflected in the concept of flexible development, called Agile [2]. The Agile methodology includes a few application methods, such as Scrum, Kanban, FDD (Feature Driven Development), as well as XP (eXtreme Programming) and RAD (Rapid Application Development). The Agile approach has four core values and twelve principles declared in the manifesto [9]. The implementation of information systems in line with these values and principals should become more efficient. The features of implementing ERP-systems based on the Agile manifesto include:

  • maximum involvement of customers in project tasks;
  • multiple modification of program prototypes that are regularly demonstrated to the customer and transferred to the production environment;
  • readiness and encouragement of changes in business requirements, providing the necessary feedback loop.

To get comments on the development, the program prototype is periodically shown to the customer. Bugs identified during the demonstration are included in the next iteration as additional refined business requirements. It is the customer who distributes the requirements for each iteration, moreover, priority of business needs may change once iteration is completed. Thus, the client decides what and when will be implemented in terms of the functionality of the software solution.

4. Uncertainty in the development of software systems

Misunderstanding of what a developed function or graphical user interface should look like to meet the initial business requirements can be avoided by regular communication with the client. Let's call this type of uncertainty technological, which characterizes misunderstanding of what a developed solution should look like and what it should do.

Hundreds and sometimes thousands of requirements are identified in ERP projects from scratch and rollout. Prioritization of business requirements is carried out according to the following approach: legal requirements that are mandatory in Russian Federation processed at first, then requirements that ensure business continuity and heavily reduce manual work. Such requirements are classified as obligatory for implementation. Usually, mandatory business requirements are clearly formulated and do not need to be clarified. Optional requirements have a low priority.

A lot of questions in the implementation project are caused by low-priority business requirements. Roughly formalized requirements are characterized by uncertainty, which is often called business uncertainty. Business uncertainty is defined by unformalized, contradictory and often incomplete requirements for developing program. There are technological and business uncertainties defined by the uncertainty of instruments and the finite uncertainty in [2]. The cascade implementation model minimizes both uncertainties already at the initial stages with the help of assumptions. On the other hand, iterative and spiral models allow for uncertainty and reduce it from iteration to iteration.

The use of cascade, iterative and spiral models for developing software systems under uncertainty

Fig. 1. The use of cascade, iterative and spiral models for developing software systems under uncertainty 

There is a matrix demonstrating the use of waterfall and multi-pass models to implement information systems under uncertainty (see figure 1,) described in paper [10]. The matrix is applicable to develop any software system and is an adapted version of the strategic management and organizational dynamics model introduced by Ralph Stacy. It was said before, only 30% of business requirements can be covered by ERP-system configuration, the rest requires development. The feature of ERP-system customization is that technological uncertainty is minimized, due to configuration allows you to cover requirements mainly one way without any other options. Thus, the Agile methodology is reasonable to use in ERP-system modification projects but not in customization projects. Taking into account the paper [11], explaining the use of the Agile Scrum method in SAP projects, it can be formulated that the Agile approach is applicable for projects of the evolution of ERP-systems.

The use of ERP-systems allows you to automate production, sale, banking and many other types of organizations. The functionality of the information system is built based on existing business objects interacting with each other and describing business processes, as well as potential enhancement points used to enrich the software system. Modification of any ERP-system is carried out under technical constraints and has predictable number of changes, so it is wrong to talk about the presence of technological uncertainty. Summarizing the above hypotheses, let’s shape the following statement: ERP-system implementation projects characterized by a limited number of business objects and functions to meet new requirements have minimal technological uncertainty and high business uncertainty.

New state laws that are obligatory in Russian Federation, their variability, ambiguity are the main reasons for business uncertainty. If it is not clear what will change in the law, when the changes will come into force, whether there will be a transition period, it is quite difficult to design and build a program that meets the originally formulated requirements. This leads to the fact that quite working applications are created, but they will not be able to ensure end-to-end business processes of the enterprise. The question of implementing applications is related to the basic principles of software development, let's look at them in more detail.

5. Principals of design and build of software systems

There are several rules that the designed and developed RICEF program must comply with (RICEF is an acronym of the possible software types) [12-13]. For instance, the application must be scalable with an increase in the number of users, flexible to future changes, solve problems optimal way and so on. The principles of software development are grouped into the following topics:

  • system control theory, specifying program control, feedback loop and compensation principals;
  • system analysis, defining the rules of functionality, evolution and uncertainty;
  • programming, characterizing modularity, functional selectivity and reliability of software systems.

It is necessary to consider the rules of evolution and functionality from the above list in more details. Each program undergoes changes, for example, due to new legal requirements, an increase in the number of end users or data volume. The principle of evolution determines the need to design ERP programs taking it into account. Therefore, each program in ERP-systems successfully operates with all kinds of objects and data types, as well as for various organizational levels of the enterprise.

Graphical illustration of the principal of functionality (A) and an example of its realization in the SAP ERP system (B)

Fig. 2. Graphical illustration of the principal of functionality (A) and an example of its realization in the SAP ERP system (B) 

The structure of the developed program should be completely determined by the initially formulated business requirements, which is the basis of the principle of functionality. Thus, a complex program consisting of a great number of buttons, menu items and screens is the result of an unsuccessful attempt to resolve various business problems by means of a single software program (see figure 2). The development of an automated workplace that combines many programs, each of them can be run independently, is an exception to this rule.

Managing new business requirement in one-pass (A) and (B) multi-pass implementation models

Fig. 3. Managing new business requirement in one-pass (A) and (B) multi-pass implementation models 

The procedure of realization business requirements in software systems based on waterfall and multi-pass implementation models using the principle of functionality can be presented as follows. Once requirements are shaped, functional specifications are to be prepared or their implementation is planned for the next development rounds. Then the application is built and tested which leads to clarification of requirements, i.e. new requirements are identified, detailing the original ones. This helps us to formulate the following statement: the waterfall model in ERP-system implementation projects allows you to realize refined requirements under separate independent subprojects by creating change requests, unlike multi-pass models, where new requirements are prioritized and processed in the next development rounds.

New requirements are often included free of charge in the current scope of ERP project implemented using the waterfall model, when the total efforts to realize refinements do not exceed the agreed amount, for example, three man-days (see figure 3). Following the above figure, it can be summarized that both models allow you to manage changes in the initial requirements, providing visibility, flexibility and traceability through the use of regulated procedures.

6. Business uncertainty in the development of ERP-systems

The above statement applies if refined business requirements complement the original ones. Using the principle of evolution as a basis for designing and building software systems allows you to preserve the original architecture of the application without violating the rule of functionality. There is high business uncertainty in real ERP-system implementation projects. For instance, there are initial requirements 1-2 for a process, for which software development is designed and built according to the principal of functionality (see figure 4). Business uncertainty leads to a completely new requirement 3, which is related to the same process and requires a considerable reworking of the original architecture of the solution. In this case, the behaviour is similar to the one given in figure 3, but there is a dilemma: to completely modify the existing program and save time by violating the principal of functionality or to develop a brand-new application that implements all three requirements, ensuring compliance with the rule of functionality, but requiring a lot of effort.

Violation of the principal of functionality when processing a new requirement

Fig. 4. Violation of the principal of functionality when processing a new requirement 

It does not matter which method is chosen, there will be a need to retest the functionality related to requirements 1-2. Therefore, business uncertainty leads to significant changes in the already built software system, zeroing out previous results. Such changes are impossible to predict and the use of modern Agile approaches cannot avoid it. Let’s summarize the above in the following statement: business uncertainty creates new requirements. To meet these requirements, essential changes are needed in already developed applications. The amendments cannot be avoided or planned in any ERP-system implementation models.

Table 1. The use of ERP-system implementation models in case of minimal technological uncertainty
Business uncertainty Model Project type Realization type
High Waterfall From scratch and rollout Configuration and development
Evolution Configuration
iterative and spiral
(Agile methodology)
Evolution Development
Low Waterfall From scratch and rollout Configuration and development
Evolution Development

Despite the growing popularity of multi-pass development models, the Agile methodology does not provide significant advantages in ERP-system implementation projects in comparison with the waterfall approach. The Agile methodology is focused on a high technological uncertainty, which is avoided in ERP-projects. None of the classical implementation models can reduce the high business uncertainty, so their use is equivalent. Waterfall and multi-pass models allow you to effectively solve the problems of developing complex software systems, while using different organizational procedures and technical methods. Taking into account the introduced statements, we will refine the use of the basic ERP-systems implementation models described in [11] (see table above).

The use of waterfall and multi-pass models in ERP-system implementation projects

Fig. 5. The use of waterfall and multi-pass models in ERP-system implementation projects 

Figure 1, presented in chapter 4, demonstrates a matrix of the use of information system implementation models depending on business and technological uncertainties. Let’s update the matrix to use it in ERP-systems implementation projects based on the table (the table is given above). To do this, it is necessary to exclude the area of high technological uncertainty, add the cascade model to the first sector and limit the use of Agile methodology only to ERP-systems evolution projects that require development. An updated matrix of the use of waterfall, iterative and spiral models in ERP projects under uncertainty is shown in the figure 5.

7. Conclusions

The functionality of corporate information systems is limited by a given number of technical tools that allow you to implement various requirements for business processes. There is minimal technological uncertainty in ERP-systems implementation projects. However, implementation projects are characterized by business uncertainty admitting fuzzy initial requirements for the system. The cascade implementation model is applicable in the case of minimal business uncertainty. The average level of uncertainty allows the use of both waterfall and multi-pass models, each model can manage refined requirements. The high business uncertainty violates the fundamental principle of functionality using in program development, thus the choice of the implementation model is not so critical.

Summarizing the results of this paper, it should be noted each ERP-systems implementation model has advantages and disadvantages, allows developing software solutions using different techniques and, unfortunately, is helpless against uncertainty of business requirements [14]. The choice of the implementation model should be made consciously, based on the project regulations and objectives, considering the experience of the project team and technical feasibility, and not guided by fashion trends and novelties. 


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Выходные данные

Stepanov, D.Y. (2023). The Theory of Corporate Information Systems. In: Radionov, A.A., Gasiyarov, V.R. Advances in Automation IV. RusAutoCon 2022. Lecture Notes in Electrical Engineering, vol 986. Springer, Cham. https://doi.org/10.1007/978-3-031-22311-2_3 – URL: https://stepanovd.com/science/article/143-2022-2-planningtechnique.

Using waterfall, iterative and spiral models in ERP-system implementation projects under uncertainty