Open access peer-reviewed chapter

Qualitative Analysis of Different CRM Evaluation Models

Written By

Christoph Weiss, Johannes Keckeis and Manfred Kofler

Submitted: 13 May 2019 Reviewed: 17 September 2019 Published: 26 November 2019

DOI: 10.5772/intechopen.89776

From the Edited Volume

Customer Relationship Management and IT

Edited by Danil Dintsis

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Abstract

Customer relationship management (CRM) systems help companies to manage their business processes. Specially for sales, campaigns, contact management, etc. The simpler and more efficient the business processes are executed, the more profitable these companies can be. Therefore, the process of selecting and evaluating a CRM system is an important success factor for each company in every industry and in every company size. The qualitative analysis of CRM evaluation models examines the necessary phases and activities for selecting a new CRM system. It is important to go through the relevant phases in the selection in order to be able to make a decision in a structured manner.

Keywords

  • analyze
  • business management
  • CRM
  • customer relationship management
  • criteria
  • decision
  • evaluation
  • evaluation models
  • normalize
  • market information
  • model
  • negotiation
  • project
  • requirements
  • selection
  • solution
  • system

1. Introduction

A customer relationship management (CRM) system is a business management software [1]. CRM software solutions usually include relevant modules for managing and executing business processes in a company such as operational CRM processes (marketing processes, sales processes, or service processes), analytical CRM processes (target group analysis, cross-selling analysis, or customer risk analysis), comprehensive processes (customer value analysis, customer segmentation, or customer characterization), or strategic processes (strategic analysis, strategic conception, or strategic controlling) [2]. A CRM system helps various parts of sales and marketing departments of an organization to organize and share data and knowledge, reduce costs, and improve the management of their business processes [3].

Various architectures of CRM systems exist on the market: proprietary CRM systems, modules as a part of ERP systems, and original equipment manufacturer (OEM) systems in enterprise system landscapes. CRM vendors and implementation partners offer similar bundles of functionalities in their software-products: a set of application modules that fit together. Each module includes a variety of functions [3].

There are different approaches for evaluating and implementing a CRM system. Thus, software evaluation is not a simple technical activity; it is a decision process including subjectivity and uncertainty with no possibility of arbitrary reduction [4]. As listed in the Appendix, several authors developed evaluation models with different methods between 1998 and 2017. These models are structured in different phase sequences and are used as a base for this paper.

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2. Methodology

The methodology approach is structured in two phases:

  1. Literature analysis

  2. Qualitative content analysis (word analysis)

In the first phase (literature analysis), different models in evaluating CRM systems are identified and used as a basis to develop a new CRM evaluation model. Twenty-one different CRM evaluation models have been identified (see Appendix: Table 16).

In the second phase, all identified papers are processed via a qualitative content analysis (word analysis). In this analysis, sources, levels, phases, activities, and tasks are qualitatively coded. Identical or similar phrases are combined and derived [5] as shown in Table 1.

Source Level Phase Original wording Activity
Q029E01001 E01 Requirements Defining requirements: first requirements and then software Define requirements
Q253E01002 E01 Requirements Definition of requirement Define requirements
Q139E02012 E01 Requirements Develop CRM request matrix Define requirements

Table 1.

Example of word analysis.

Within the word analysis, terms are summarized as shown in the following examples [6]:

  • “analyze” (analyze, check, identify, verify, …)

  • “define” (appoint, define, form, setup, organize, …)

2.1 Different ways of sequencing

Based on the word analysis, the sequences of phases and activities are determined. Three different calculation types are used to determine the sequences:

  1. The phases or activities were normalized in each evaluation model, and an average value was calculated.

  2. Average value is given by the sum of the multiplication of nominations per phase/activity number, and the frequency of the mentions in this phase/activity is divided by the amount of nominations per phase/activities.

  3. The mean is determined from the occurrence of the identified first and last phase or activities of the analyzed models.

Phase/activity Nomination in phase/activity A B C D

∑: number of entries in the 21 papers.

A: average of phase/activity numbers (phases including nominations).

B: sum of (amount of nominations per phase * phase number)/amount of nominations per phase/activity.

C: normalized phase/activity (see normalization formula in the appendix: Table 17).

D: ranking (column C).

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3. Analysis

The number of phases within the different CRM evaluation models varies between two and eight phases. In this analysis, only phases which are listed in minimum three of the 21 papers mentioned before were considered. On average 4,48 phases are present. Table 2 shows the considered phases.

The following terms are mentioned in the papers on the one hand as an activity in a selection phase and on the other hand as a phase: definition of requirements, longlist, market information, presentation, negotiation and contract, and decision.

Each phase is structured with different activities. In this analysis, only activities which are listed at least two times in the phases mentioned before are considered. In the 21 papers, these activities are called sub-phases or detail descriptions. Further identified and analyzed activities will be added after each phase.

3.1 P1 condition phase

The main activity in the first phase is clarification and definition of the strategy. This concerns the corporate strategy as well as the IT strategy and CRM strategy (Table 3).

Phase Nomination in phase A B C D
(Business)process analysis 1, 4 3 2.5000 2.0000 0.1429 3
Analyze 1, 2, 3, 7 9 4.0000 2.4444 0.2974 5
Conditions 1 3 1.0000 1.0000 0.0000 1
Decision 3, 4, 5, 8 7 5.5000 5.2857 1.0000 13
Evaluation 2, 4 3 3.0000 3.3333 0.6667 8
Longlist 2, 3 4 2.5000 2.5000 0.3571 7
Market information 1, 2, 3, 4, 5 6 3.0000 2.6667 0.3262 6
Negotiation and contract 3, 5, 7 3 5.0000 5.0000 0.9524 12
Presentation 3, 4, 7 10 5.0000 4.2000 0.6888 10
Project initialization 1, 2 5 1.5000 1.2000 0.0286 2
Requirement definition 1, 2, 3 11 2.0000 1.8182 0.2576 4
Selection 1, 2, 3, 4, 5, 6, 8 22 4.5000 3.3182 0.6683 9
Shortlist 3, 4, 5 4 4.0000 4.0000 0.7667 11

Table 2.

Considered phases.

Activities Nomination in phase A B C D
Define strategy 1 2 1.0000 1.0000 0.0000 1

Table 3.

Activities in the condition phase.

3.1.1 Other activities

It is important to differentiate the CRM evaluation project from other projects in the company and to focus on the selection and implementation of CRM processes with a new CRM system. Furthermore, basic requirements are clarified.

3.2 P2 project initialization phase

In Table 4, four activities are identified. At the beginning of the project initiation, a project manager is appointed by the management. The project manager defines the project and elaborates the project assignment in detail. One focus is detailing the goals, which have been defined by the management in the condition phase. Following this, the project will be launched.

Activities Nomination in phase A B C D
Define a project 1, 4 3 2.5000 3.0000 0.4000 4
Define goals 1, 3 2 2.0000 2.0000 0.2000 3
Define project manager 1 2 1.0000 1.0000 0.0000 1
Start project 1, 2 2 1.5000 1.5000 0.0714 2

Table 4.

Activities in the project initialization phase.

3.2.1 Other activities

A project sponsor is set by the management to give the project the necessary importance in the company. The project is justified by the project manager who defines the project team. The detailed project scope is agreed with the project team and the project client. Another activity includes conducting a preliminary study on the feasibility of the CRM project. A kickoff is prepared and carried out. A detailed risk analysis is done and a risk management for the project is established. On the one hand the project budget is defined and on the other hand a exact timetable is defined and formulated.

3.3 P3 (business) process analysis phase

In the process analysis phase, all necessary business processes are defined. This phase includes identification, documentation, and evaluation of all CRM processes. In further step criteria for the evaluation of CRM systems, CRM providers and CRM business processes are defined (Table 5).

Activities Nomination in phase A B C D
Develop processes 1, 4 2 2.5000 2.5000 0.2143 2
Set criteria 1, 2 2 1.5000 1.5000 0.5000 1

Table 5.

Activities in the project initialization phase.

3.3.1 Other activities

In business process analysis, processes can be further developed and modeled.

3.4 P4 requirement definition phase

In the requirement definition phase, the requirements (business and technical view) are determined, analyzed, defined, and prioritized. Specifications are developed for detailed requirements. These requirements affect the CRM processes, CRM systems, and CRM providers. The detailed requirements are listed in a requirement catalog, which is the basis for the specifications (Table 6).

Activities Nomination in phase A B C D
Analyze requirements 1 2 1.0000 1.0000 0.0000 1
Create requirement catalog 1, 2, 5 3 3.0000 2.6667 0.4444 5
Create specifications 4, 5 2 4.5000 4.5000 0.7143 6
Define requirements 1, 2, 3 17 2.0000 1.5294 0.1863 4
Determine requirements 1, 2 4 1.5000 1.2500 0.0000 1
Prioritize requirements 1 2 1.0000 1.0000 0.0000 1
Set criteria 3, 4 3 3.5000 3.3333 0.9167 7

Table 6.

Activities in the requirement definition phase.

3.4.1 Other activities

Selection criteria are weighted, and the decision criteria are prioritized. CRM processes are developed. Target processes for the processing of CRM activities are defined.

3.5 P5 analysis phase

An actual analysis of all relevant CRM business processes must be carried and worked out. This includes all needs for functions and processes of the CRM systems. Furthermore, the future (CRM) processes will be developed, and the selection criteria will be evaluated (Table 7).

Activities Nomination in phase A B C D
Analysis needs 2 2 2.0000 2.0000 0.2500 2
Evaluate criteria 2, 3 4 2.5000 2.2500 0.4167 4
Capture software 2 2 2.0000 2.0000 0.3330 3
Develop processes 2, 3 2 2.5000 2.5000 0.4167 4
Perform an actual analysis 1, 2, 3 4 2.0000 1.7500 0.1214 1
Perform analysis 2, 7 2 4.0000 4.5000 0.6786 6

Table 7.

Activities in the analysis phase.

3.5.1 Other activities

The following points are defined:

  • All necessary (CRM) processes evaluation criteria

  • Quantity structure such as number of offers, customers, etc.

  • IT infrastructure

  • CRM improvement potentials

3.6 P6 market information phase

Within the market information phase, not only CRM systems but also CRM vendors and CRM implementation partners are determined and structured in an adequate market overview (Table 8).

Activities Nomination in phase A B C D
Conduct market research 3, 4, 5 3 4.0000 4.0000 0.4857 3
Market overview 1, 2 2 1.5000 1.5000 0.2500 2
Search providers 1 2 1.0000 1.0000 0.0000 1

Table 8.

Activities in the market information phase.

3.6.1 Other activities

In P6, a first longlist is created. This is done based on the evaluation of the market data. Detailed information is collected from the providers in the form of a specification.

3.7 P7 longlist phase

3.7.1 Other activities

A longlist of CRM systems and CRM provider (vendor and implementation partner) is created (Table 9). All possible CRM systems and CRM providers are listed. Based on the defined criteria, the CRM systems and CRM providers are evaluated.

Activities Nomination in phase A B C D
Create longlist 2, 3 3 2.5000 2.3333 0.3810 1

Table 9.

Activities in the longlist phase.

3.8 P8 evaluation phase

3.8.1 Other activities

In addition to the (CRM) business processes (Table 10), the IT infrastructure is also evaluated.

Activities Nomination in phase A B C D
Evaluate criteria 2, 4 2 3.0000 3.0000 0.6250 1

Table 10.

Activities in the evaluation phase.

3.9 P9 selection phase

The selection can be done over 1-n stages (basic selection or preselection, fine selection, and final selection). Depending on size and/or complexity of the evaluation, all three or even two sub-phases can be necessary (Figure 1).

Figure 1.

Selection phases.

The proposals from the selection phase are compared and evaluated according to predefined criteria. Presentations and workshops will be held for the decision-making of CRM software and CRM providers. An implementation plan is created (Table 11).

Activities Nomination in phase A B C D
Compare offers 3, 4, 5 4 4.0000 3.0000 0.5333 6
Create implementation plan 4, 5 2 4.5000 4.5000 1.0000 12
Evaluate criteria 1, 2, 4 5 2.5000 1.8000 0.5000 5
Make decision 3, 5, 7 4 5.0000 5.5000 0.9643 11
Make rough selection 1, 4, 5 3 3.0000 3.3333 0.4095 4
Make selection 1, 2, 3, 4, 6, 8 10 4.5000 3.4000 0.8167 10
Perform fine selection 2, 4, 6 4 4.0000 3.5000 0.7381 8
Perform preselection 1, 2, 5, 6 9 3.5000 2.5556 0.2170 3
Perform presentations 2, 4 3 3.0000 2.0000 0.1667 2
Perform workshops 3, 6 2 4.5000 4.5000 0.6500 7
Select software 2, 3, 4 3 3.0000 3.0000 0.8056 9
Tender 1, 3, 6 3 3.5000 3.3333 0.1000 1
Perform final selection 6, 8 2 7.0000 7.0000 1.0000 12

Table 11.

Activities in the selection phase.

3.9.1 Other activities

In the selection phase, it may be necessary to carry out market research again. Possible first tests of CRM systems are completed. Visits to reference customers of the CRM providers are prepared and carried out. For this, questions are prepared, and potential participants are determined. CRM business cases are defined. Possible CRM providers are contacted and the answered specifications pre-evaluated. Contract negotiation contracts are drafted, and initial negotiations are carried out. Detailed requirements are determined, the essential selection criteria are defined, and, if necessary, the criteria are weighted.

3.10 P10 presentation phase

During P10 phase, 1-n presentations will be held. This can also be considered as a proof of concept (Table 12).

Activities Nomination in phase A B C D
Perform presentations 3, 4, 7 8 4.2500 8 0.6824 1
Proof of concept 4 2 4.0000 2 0.7143 2

Table 12.

Activities in the presentation phase.

3.10.1 Other activities

An agenda must be created for vendor presentations. The vendor presentations should be moderated. A documentation (e.g., minutes) of each vendor presentation is created. Each vendor presentation is rated by a defined Team via defined questionnaire. For the vendor presentations, data for the prototype is provided. The activities for the vendor presentations are also valid for the proof of concept.

3.11 P11 shortlist phase

3.11.1 Other activities

A shortlist of CRM systems and CRM providers (vendors and implementation partners) must be created (Table 13). All CRM systems and CRM providers from the reduced longlist are collected in the list. Based on previous defined detailed criteria, the CRM systems and CRM providers are evaluated and reduced to a shortlist.

Activities Nomination in phase A B C D
Create shortlist 3, 4, 5 4 4.0000 4.0000 0.7667 1

Table 13.

Activities in the shortlist phase.

3.12 P12 negotiation and contract phase

The focus in this phase is to design the contracts (project contract, software contract, maintenance contract) and conduct contract negotiations (Table 14).

Activities Nomination in phase A B C D
Carry out negotiations 3, 7 2 5.0000 5.0000 0.9286 1

Table 14.

Activities in the project initialization phase.

3.12.1 Other activities

The negotiation strategy is defined, and the following important contract elements are identified:

  • Costs for licenses, consulting, development

  • Terms of payment

  • Travel expenses

  • Liability

  • Warranty

  • Delay

  • Approval conditions

  • Service-Level-Agreements (SLA)

  • etc.

3.13 P13 decision phase

In the decision phase, all decisions are collected, and a management summary is given. Final tests provide information and form the final basis for a definite decision (Table 15).

Activities Nomination in phase A B C D
Final testing 1, 2 2 1.5000 1.5000 0.1250 2
Make decision 3, 4, 5, 6, 8 8 5.5000 5.2500 1.0000 3
Summarize criteria 1 2 1.0000 1.0000 0.0000 1

Table 15.

Activities in the decision phase.

3.13.1 Other activities

Possible reference customers (clients) of the final vendor are identified, contacted, and visited. During reference visits, the implementation project, the industry experience of the consultants, and the ongoing support will be discussed. The final contract negotiations are carried out. In the final phase, the most suitable system and the vendor or implementation partner are selected.

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4. Conclusion

The study is interesting since viewpoints from a literature perspective as well as from a business side have been considered. The results of the qualitative content analysis (Figure 2) offer the possibility of the individual design of a procedure model for the selection of CRM systems.

Figure 2.

Thirteen-stage selection model.

The selection model can be changed or adjusted if necessary. This applies to the analyzed phases as well as to the respective activities within the phases.

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5. Future work

In the qualitative analysis of CRM evaluation models, 13 phases including specific activities were identified. Based on this literature review, it is planned to conduct expert interviews. On the basis of these expert interviews, a new CRM evaluation model will be defined an afterwards tested via a quantitative analysis to confirm the results. Based on this new model, it is planned to develop guidelines how the model can be used.

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Model name Number phases Model type Procedure Document type
5 step CRM software selection guide: a pragmatist’s guide to CRM software selection [7] 5 Selection Guide Product folder
CRM Evaluierung [8] 3 Evaluation Product folder
CRM implementation method [9] 5 Selection Processes Conference paper
Software selection steps [10] 3 Selection Steps Journal paper
Überblick über das Referenz-Vorgehensmodell [11] 8 Selection Reference model Dissertation
Phasen der Softwareauswahl [12] 8 Selection Processes Book
Einführung eines SFA-Systems [13] 3 Implementation Phases Technical article
Selektionsprozess CRM-System [14] 5 Selection Processes Essay
Phasen der Softwareauswahl [15] 3 Selection Phases Technical article
CRM-Softwareauswahl [16] 6 Selection Guide Guide
CRM-Auswahl in vier Schritten zum richtigen System [17] 4 Selection Steps Consultation
CRM Beratung [18] 2 Implementation Stages Consultation
Übersicht über das CRM-Selektionsmodell [19] 3 Selection Phases Technical article
Auswahlprozess [20] 4 Selection Phases Consultation
Ideale Vorgehensweise bei einer Kampagnenmanagement-Auswahl [21] 8 Selection Consultation
Methodik und Vorgehen: Best Practice CRM-Entscheidungstrichter [22] 4 Evaluation Steps White paper
Drei Phasen (und ein Kick-Off) zur Auswahl ihrer CRM-Software [23] 4 Selection Phases White paper
Auswahl und Einführung von CRM-Systemen [24] 6 Selection Road map Study
Evaluationsprozess für CRM-Systeme [25] 3 Evaluation Phases Bachelor thesis
CRM-Projekt [26] 2 Selection Phases White paper
Vorgehensweie im Überblick [27] 5 Selection Phases Presentation slides

Table 16.

Overview of the evaluation models.

# of phases Split # of phases Split # of phases Split # of phases Split
1 0.0000 1 0.0000 1 0.0000 1 0.0000
2 1.0000 2 0.5000 2 0.3333 2 0.2500
3 1.0000 3 0.6667 3 0.5000
4 1.0000 4 0.7500
5 1.0000
# of phases Split # of phases Split # of phases Split # of phases Split
1 0.0000 1 0.0000 1 0.0000 1 0.0000
2 0.2000 2 0.1667 2 0.1429 2 0.1250
3 0.4000 3 0.3333 3 0.2857 3 0.2500
4 0.6000 4 0.5000 4 0.4286 4 0.3750
5 0.8000 5 0.6667 5 0.5714 5 0.5000
6 1.0000 6 0.8333 6 0.7143 6 0.6250
7 1.0000 7 0.8571 7 0.7500
8 1.0000 8 0.8750
9 1.0000

Table 17.

Normalization formula.

References

  1. 1. Piazolo F, Paa L, Keckeis J. IT-embedded strategic management. Mittelstand Kompakt–Information im Fokus. 2012;2(2):24-27
  2. 2. Hippner H, Hubrich B, Wilde K. Grundlagen des CRM–Strategie, Geschäftsprozesse und IT-Untertützung. Wiesbaden: Gabler Verlag; 2011
  3. 3. Perera H, Costa W. Analytic hierarchy process for selection of ERP software for manufacturing companies. The Journal of Business Perspective. 2008;12(4):1-11
  4. 4. Nikolaos P, Sotiris G, Harris D, Nikolaos V. An application of multicriteria analysis for ERP software selection in a Greek industrial company. Operational Research, An International Journal. 2005;5(3):435-458
  5. 5. Mayring P. Qualitative Inhaltsanalyse (Grundlagen und Techniken), Beltz, 12., überarbeitete Auflage. Weinheim und Basel. 2015
  6. 6. Weiss C, Kofler M, Friedemann R. Qualitative analysis of different ERP evaluation models. In: ERP Future 2016: Innovations in Enterprise Information Systems Management and Engineering (5th International Conference). Hagenberg. 2016. pp. 17-25
  7. 7. 5 Step CRM Software Selection Guide: A Pragmatist’s Guide to CRM Software Selection. [Internet]. 2007. Available from: http://www.online-crm.com/landing5step.asp [Access: 16 February 2016]
  8. 8. CRM Evaluierung. [Internet]. 2012. Available from: http://www.intense.de/sites/default/files/dokumente/05_crm_evaluierung.pdf [Access: 16 February 2016]
  9. 9. Friedrich I, Sprenger J, Breitner M. Discussion and validation of a CRM system selection approach with experts. In: AMCIS 2011 Proceedings-All Submissions
  10. 10. Colombo E, Francalanci C. Selecting CRM packages based on architectural, functional, and cost requirements: Empirical validation of a hierarchical ranking model. Requirements Engineering. 2004;9:186-203
  11. 11. Arens T. Methodische Auswahl von CRM Software (Ein Referenz-Vorgehensmodell zur methodengestützten Beurteilung und Auswahl von Customer Relationship Management Informationssystemen) [dissertation]. Abt. Wirtschaftsinformatik: Georg-August-Universität, Göttingen; 2003
  12. 12. Spielberg D. Enterprise Marketing Management (Informationslogistik für das Marketing von morgen). Wiesbaden: Springer; 2013
  13. 13. Lossau S, Der digitale Weg zum Kunden. Diebold Management Report, Nr. 8/9, Düsseldorf, 1998
  14. 14. Beye D. Auswahl von CRM-Systemen und Technologiepartnern-Kriterien, Prozesse, und Erfolgsfaktoren [Seminararbeit]. Lüneburg: Leuphana Universität Lüneburg; 2012
  15. 15. Schwetz W. CRM Softwareauswahl mit System: Drum prüfe, wer sich ewig bindet ... Freiburg München Berlin: Rudolf Haufe Verlag; 2007. pp. 163-190
  16. 16. CRM-Softwareauswahl: Ein Leitfaden [Internet]. 2013. Available from: http://www.softselect.de/deu/documents/view/188 [Access: 28 May 2016]
  17. 17. CRM Evaluation [Internet]. Available from: http://www.advanis.ch/de/beratung/crm-evaluation.html [Access: 28 May 2016]
  18. 18. CRM Beratung [Internet]. Available from: http://www.schwetz.de/crm-beratung.html [Access: 28 May 2016]
  19. 19. Passgenaue CRM-Lösungen finden [Internet]. Available from: http://www.absatzwirtschaft.de/passgenaue-crm-loesungen-finden-2-19306/ [Access: 28 May 2016]
  20. 20. Vorgehensmodell Toolauswahl [Internet]. 2015. Avaliable from http://cintellic.com/Vorgehensmodell-Toolauswahl.php [Access: 28 May 2016]
  21. 21. Praxistipps für die erfolgreiche Kampagnenmanagement-Toolauswahl [Internet]. Available from: http://cintellic.com/Praxistipps-Kampagnenmanagement-Toolauswahl.php [Access: 28 May 2017]
  22. 22. Bärwolff O, Panser F. CRM-Evaluation (Wie finde ich die richtige Software für mein Unternehmen?). Erfurt: TecArt GmbH; 2016
  23. 23. Rönn S. Die 3 Phasen Ihrer CRM-Softwareauswahl-Schritt für Schritt zum richtigen CRM-System (Ein Whitepaper der ec4u expert consulting ag). ec4u expert consulting ag. In: Karlsruhe. 2016
  24. 24. Torggler M. Einsatz von CRM-Systemen (Eine empirische Studie zum praktischen Einsatz von CRM-Systemen in Österreich). Wiener Neustadt: Zentrum für Business IT-Tools, Fachhochschule für Wirtschaft und Technik; 2007
  25. 25. Zimmermann R. Customer relationship management (CRM)–Systemevaluation für Mittelstands-und Großunternehmen [bachelor thesis]. Hochschule für angewandte Wissenschaften: Ernst-Abbe-Fachhochule Jena; 2017
  26. 26. Auswahl & Einführung einer CRM-Softwarelösung (Whitepaper) [Internet]. 2013. Available from: http://pisasales.de [Access: 17 September 2017]
  27. 27. Kainer H, Alznauer T. Erfahrungen bei der Bewertung und Auswahl eines CRM-Anbieters. Arbeitskreis “Customer Relationship Management-Vom Konzept zum Erfolg”. Hameln: Hochschule Weserbergland; 2003

Written By

Christoph Weiss, Johannes Keckeis and Manfred Kofler

Submitted: 13 May 2019 Reviewed: 17 September 2019 Published: 26 November 2019