Modelling the Costs of Preserving Digital Assets

Transcription

1 Modelling the Costs of Preserving Digital Assets Ulla Bøgvad Kejser 1, Anders Bo Nielsen and Alex Thirifays 2 1 The Royal Library, Copenhagen, Denmark, ubk@kb.dk 2 The Danish National Archives, Copenhagen, Denmark, abn@sa.dk and alt@sa.dk Abstract Information is increasingly being produced in digital form, and some of it must be preserved for the longterm. Digital preservation includes a series of actively managed activities that require on-going funding. To obtain sufficient resources, there is a need for assessing the costs and the benefits accrued by preserving the assets. Cost data is also needed for optimizing activities and comparing the costs of different preservation alternatives. The purpose of this study is to analyse generic requirements for modelling the cost of preserving digital assets. The analysis was based on experiences from a Danish project to develop a cost model. It was found that a generic cost model should account for the nature of the organisation and the assets to be preserved, and for all major preservation activities and cost drivers. In addition, it should describe accounting principles. It was proposed to develop a generic cost model with specific profiles to represent different preservation scenarios. Authors Ulla Bøgvad Kejser holds a PhD in Conservation-Restoration Science from the Royal Danish Academy of Fine Arts, School of Conservation. She is a preservation specialist at the Royal Library in Denmark working in the areas of preservation imaging, preservation planning, and curation of both physical and digital collections, especially images. Her current research focuses on modelling the costs of digital preservation. Anders Bo Nielsen holds a master in economics from the University of Copenhagen (economic history and IT as specialty) from 1997 and a master in IT (software development as specialty) from the IT University of Copenhagen from He is a principal consultant at the Department of Appraisal and Transfer at the Danish National Archives, where he has been employed since Alex Thirifays is an archivist at The Danish National Archives. He obtained his MA in history in He has been working as an IT consultant for 6 years, and is since 2007 working with digital curation, particularly cost modelling, preservation planning and strategic issues. He has developed the Cost Model for Digital Preservation (CMDP) together with Anders Bo Nielsen and Ulla Bøgvad Kejser and published several papers and reports on this work. 1. Introduction All over the world societies produce more and more information in digital form, either directly from computers and other electronic devices or by digitisation of analogue assets. Some of this information is

2 considered worth preserving, e.g. critical business information, personal memories or cultural heritage documents. Preservation and access to digital assets is dependent on technology; the physical streams of bits constituting the information must remain intact and accessible through current systems, and the intellectual content of the information must remain usable over time. Counteracting the constant threat from technological obsolescence requires a series of actively managed activities, including emulation of systems or migration of formats. Facilities with adequate hardware and software must be in place as well as power to keep the systems running. In addition, people with the necessary skills to maintain the systems and act as curators of the digital assets must be available. The required preservation activities and the flow of information are described at an abstract level in the ISO standard for an Open Archival Information System (OAIS) Reference Model. 1 The OAIS functional model divides the lifecycle in seven main functional entities: Ingest, Archival Storage, Data Management, Preservation Planning, Administration, Access and Common Services. The entities are each comprised of several functions described in detail in the standard. Organisations dedicated to long-term preservation are termed trustworthy digital repositories. 2 In practice repositories are implemented in various ways according to on the one hand, the available resources, and on the other, the nature of the organisation and the assets in its trust. The repository may e.g. be private or public, it may have a business need or a legal mandate to preserve, and the duration of preservation may be definite or infinite. The assets, whether individual objects, or groups of objects, may represent documents, books, images, films, web pages, etc. in various qualities. Here quality is used as a collective name for different properties of the assets relating to their content, context, appearance, structure and behaviour 3 as well information security, 4 including authenticity, confidentiality, integrity and availability. On a more detailed level quality also relate to format types, a book may e.g. be saved as a pdf or word document, or as tiff images; preservation strategies, whether based on migration or emulation; and how the repository is organised, e.g. as a distributed or centralised system. In order to allocate sufficient resources for digital preservation activities, repository managers obviously need to know how much they cost. However, as may be perceived from the above examples of the diversity in the digital preservation scenarios and the comprehensiveness of preservation activities in depth as well as in breadth, it is a complex task to account for the costs and the cost drivers of digital preservation. Furthermore, as opposed to traditional preservation of e.g. paper-based records, digital preservation services have not yet fully matured. This means that costing of digital preservation is not only complicated by constantly evolving technologies, but also because best practice has not been established. Over the last decade several cost models have emerged to support cost assessment, some aimed at specific sectors or materials, others more generic in nature: The National Archives of the Netherlands 1 Consultative Committee for Space Data Systems (CCSDS), Reference Model for an Open Archival Information System (OAIS), Magenta Book, Recommended Practice, CCSDS M-2, 2012 (ISO14721:2003), accessed August 2012, 2 Consultative Committee for Space Data Systems (CCSDS), Audit and Certification of Trustworthy Digital Repositories. CCSDS M-1, Magenta Book, 2011, (ISO 16363:2012), accessed August The InSPECT (Investigating the Significant Properties of Electronic Content Over Time) project, Significant Properties Report, 8, 2009, accessed August 2012, 4 ISO/IEC 2700:2009, Information technology Security techniques Information security management systems Overview and vocabulary, 3,

3 cost model for digital preservation, 5 the NASA Cost Estimation Tool (CET), 6 the LIFE Costing Model, 7 the Keeping Research Data Safe (KRDS) model, 8 the Cost Model for Digital Archiving, 9 the Cost Model for Digital Preservation (CMDP), 10 the DP4lib cost model, 11 the PrestoPRIME cost modelling tools, 12 the California Digital Library cost model 13, and the Economic Model of Storage. 14 The costs of the preservation activities cannot be viewed in isolation, but need to be balanced against the benefits that they represent to stakeholders. These aspects of the economies of digital preservation were investigated by the Blue Ribbon Task Force on Sustainable Digital Preservation and Access, and resulted in two comprehensive reports 15,16 and initiated the development of the Economic Sustainability Reference Model. 17 To this end the KRDS project has also developed tools for analysing benefits 18 and in the Cost Model for Digital Archiving benefits are expressed via the Balanced Scorecard methodology. 19 Strategies for funding digital preservation are also described in a recent report on alignment in digital preservation initiatives Slats, J. and Verdegem, R, Cost Model for Digital Preservation, Proceedings of the IV th triennieal conference, DLM Forum, Archive, Records and Information Management in Europe, 2005, accessed August 2012, 6 NASA, Cost Estimation Toolkit (CET), accessed August 2012, 7 Hole, B., Lin, L., McCann, P., Wheatley, P., LIFE3: A Predictive Costing Tool for Digital Collections, In: Proceedings of ipres 2010, 7th International Conference on Preservation of Digital Objects, Austria, 2010, accessed August 2012, 8 Beagrie, N., Lavoie, B., Woollard, M., Keeping Research Data Safe 2, Final Report, Charles Beagrie Limited, 2010, acccessed August 2012, 9 Palaiologk, A.S., Economides, A.A., Tjalsma, H.D., Sesink, L.B., An activity-based costing model for long-term preservation and dissemination of digital research data: the case of DANS, Int J Digit Libr, DOI /s , Springer, 2012, accessed August 2012, 10 Kejser, U.B, Nielsen, A.B., Thirifays, A Cost Model for Digital Preservation: Cost of Digital Migration. In: The International Journal of Digital Curation, Issue 1, Vol. 6, pp , accessed August 2012, 11 DP4lib Kostenmodell für Langzeitarchivierung, Kostenmodell_eines_LZA-Dienstes_v1.0.pdf 12 Addis, M., Jacyno, M., Tools for modelling and simulating migration based preservation, PrestoPRIME, 2010, accessed August 2012, PreservationModellingTools_R0_v1.00.pdf 13 California Digital Library, CDL, Cost Modeling, 14 Rosenthal, D., Economic model of Storage, November 2011, accessed August 2012, 15 Blue Ribbon Task Force on Sustainable Digital Preservation and Access, Sustainable Economics for a Digital Plant: Ensuring Long-Term Access to Digital Information, Final report, 2010, accessed August 2012, 16 Blue Ribbon Task Force on Sustainable Digital Preservation and Access, Sustaining the digital investment: Issues and challenges of economically sustainable digital preservation,(interim report), 2008, accessed August, 17 Rusbridge, C. Update on the state of the Economic Sustainability Reference Model, accessed August 2012, 18 Digital Preservation Benefit Analysis Tools, accessed August 2012, 19 Kaplan, R.S., Norton, D.P., The Balanced Scorecard: Translating Strategy into Action, Harvard Business School Press, Boston, Lunghi, M., Grindley, N., Stoklasová, B., Trehub, A., Egger, C., Economic Alignment, in Aligning National Approaches to Digital Preservation, vol. ed. N. McGovern, series ed., K. Skinner, Educopia Institute Publication, ISBN: , pp , 2012,, accessed August 2012, 3

4 Accounting for the costs of preservation activities, their relationships, variables, and underlying pre-conditions in a structured manner remains highly challenging and so far no consensus has been reached within the community on how to model the costs of preserving digital assets. In this paper we examine which cost data are needed for managing a repository, and how the costs of preserving access to digital assets are influenced by other economic factors. Based on this examination and with a view to existing cost methodologies we analyse the constituents of a generic cost model, capable of accounting for different types of assets and organisations. This work is based on experience from the Danish CMDP project ( ) in which a cost model and an associated spreadsheet tool for assessment of the cost of preserving cultural heritage materials have been developed 21. Wherever relevant the CMDP model and tool have been used to exemplify how different challenges in cost modelling may be addressed. 2. Required Preservation Cost Data 2.1 Budgeting Cost data for digital preservation is needed for preparing and controlling budgets. Repository managers need to know the total costs of all activities involved in the digital preservation lifecycle and the distribution of costs over individual activities, and groups of activities. They must also be aware of which activities are included in the preservation lifecycle and which are not. Understanding the distribution of costs is also important for identifying when the costs of specific activities fall due, e.g. when reinvestments in storage media or systems are required, and for pricing specific preservation services in relation to outsourcing. Likewise, cost data is needed for evaluating the effect of adjusting the cost of one lifecycle activity on the other activities, e.g. if the richness of metadata provided at ingest is decreased to save costs, it may induce increased costs at access. In addition, it is needed for identifying the most important costs, which in particular require careful monitoring. Managers must also know the accounting principles underlying cost figures. For example they need to know if the cost includes the full economic costs, i.e. the direct investment and operation costs, as well as indirect costs, such as the cost of general administration and facilities (overhead). If indirect costs are included they must in addition know how they have been distributed, e.g. as a percentage over all lifecycle activities, or on individual activities. Managers also need to know how possible financial adjustments, e.g. inflation, are accounted for. Likewise, they must acknowledge the assumptions on which estimates of future costs are based, e.g. are assumptions based on projections of historical data or is status quo assumed in price development. 2.2 Optimisation Cost data is also required for adjusting expenditures to the projected financing and for potential optimisation of preservation activities. Within an existing budget framework it may be possible to enhance the preservation systems and processes, without compromising the quality, and thereby improving the overall cost efficiency of the preservation activities. This may, for example, be achieved by engaging in partnerships that allow exploiting economies of scale, e.g. in the area of archival storage, or economies of scope, e.g. by providing more versions of the same asset. Going beyond the existing 21 The Cost Model for Digital Preservation, accessed August 2012, 4

5 framework, budgets may be balanced by attracting additional funding from external stakeholders or by internal re-allocation of resources within the organisation. It is also possible to adjust budgets by reconsidering the quantity and/or the level of quality of the assets to be preserved. 2.3 Evaluation of alternatives Cost data is also needed for comparing the costs of alternatives, e.g. the costs of applying different preservation strategies or the cost of increasing certain quality properties of the assets. In order to execute such comparisons managers need to be able to account for the quality of the preservation activities. If, for example, the cost of migration processes are compared it is necessary to specify, among other things, how well significant properties of the assets are preserved; how many errors in the process are acceptable and how many random samples are needed to detect errors. 2.4 Economic aspects The nature of the assets and the organisations that are responsible for preservation and access motivate stakeholders, i.e. owners, producers, and consumers of the assets, requirements for the quality of the assets. Based on these requirements the repository managers specify the quality of the assets. This value proposition represents a certain value to stakeholders and determines their willingness to pay for the assets (see Figure 1). Quality requirements Type of assets & organisation Stakeholders Value proposition Repository managers Willingness to pay Figure 1. Interactions between stakeholders and repository managers. Thus, the costs of the preservation activities and the associated quality of the digital assets and services provided by the repository must be seen in relation to the perceived value and stakeholders willingness to pay for the assets. Whenever changes in the quality of the assets occur they are likely to influence how stakeholders value the preserved assets and thereby their willingness to pay. A digitized book may e.g. gain value if the file is processed by an OCR program to make the text searchable. Likewise, making a repository s degree of trustworthiness explicit by investing in audit and certification could potentially increase revenues for a preservation service provider. Therefore managers must also be aware of the business models underlying the repository, and understand the mechanisms by which the value of assets and preservation services is driven. 5

6 2.5 Towards a generic cost model In order to optimise digital preservation activities and identify best practices it is important to account for the costs and the quality of the activities in a complete and consistent way that further allows for comparing different scenarios. Ideally, a generic cost model should apply the same methodology for accounting for the costs of all types of assets, preserved in different qualities, and by different preservation strategies, services and organisations; and it should therefore describe the required preservation activities at a conceptual and implementation neutral level. However, costs cannot be assigned on the conceptual level; it is only possible to cost actual implementations. The reason is that activities can be implemented in several ways resulting in different qualities and costs. Thus it is prerequisite to specify the actual implementations in order to assign resources to it, and cost assessments are therefore based on a series of assumptions about the quality of the assets and how they are preserved. In the CMDP project there is a loose distinction between a cost model and a tool: The CMDP model defines the principles and methods for assessing costs of preserving assets, whereas the CMDP tool makes these principles operational and enables actual cost assessment in a spreadsheet. A generic cost model should also determine the drivers of the costs in digital preservation. In addition, it should describe the principles for accounting, making financial adjustments, and projecting future costs. Based on the examination of cost data required for costing digital preservation we propose that a cost model should comprise four building blocks: Profiles, Preservation activities, Cost drivers and Accounting principles (see Figure 2). These model components are described in more detail in the following sections. Preservation activities Cost drivers Pro/iles Generic cost model Accounting principles 6

7 Figure 2. Proposed building blocks of a generic cost model 2.6 Profiles One way to map between the conceptual cost model level and specific preservation scenarios is through the use of profiles that define the context of the cost assessment. For example a profile could represent an archive with a legal mandate to preserve cultural heritage documents or a private service provider offering cloud storage. Well-described profiles could help understanding and interpreting cost figures and support cost comparisons. In the CMDP tool it is possible to add contextual information via predefined dropdown lists where users can select, among other things, the type of organisation, e.g. archive, library; the purpose of preservation, e.g. business requirement, legal mandate; and potentially also quality requirements, e.g. regarding the confidentiality of the assets. The idea is to gradually develop a database with specific cost profiles for different scenarios, which can then be used for comparing sets of cost data. 2.7 Preservation activities To ensure that the relevant costs are accounted for, the models must identify, describe and delimit all major activities in digital preservation in a complete, precise and systematic way; and describe the relationships and dependencies between the activities. From its inception the OAIS Reference Model was proposed as the basis for costing the activities in digital preservation, 22 and most cost models, including the CMDP, are more or less strictly based on the OAIS functional model. The OAIS functions are described at an abstract level that must be transformed into specific activities, which can then be allocated resources. For example, the OAIS standard states that the function Generate AIP under the functional entity Ingest may involve file format conversions. Before you can assess the costs of this function, you need to make a series of assumptions regarding the assets to be preserved, the applied preservation strategy, the technical and organisational design of the repository, and the required quality of the conversion. 23 In the CMDP project the functional descriptions in the OAIS standard and the flow between the functions were analysed to identify cost-critical activities, i.e. tasks, which take more than one-personweek to accomplish. Resources were then associated with the activities and cost dependencies identified. The resources and relationships were then expressed in mathematical formulas and made operational in the CMDP tool. So far expressions for the functional entities Ingest, Archival Storage, Preservation Planning, and Administration have been completed and implemented in the tool. The tool works by summing up the cost of the activities, functions and functional entities over the costing period. 2.8 Accounting principles A generic cost model must define the applied accounting principles, i.e. the standards, rules and procedures used for recording and reporting accounting information to obtain consistency and accuracy in 22 Sanett, S., Toward developing a framework of cost elements for preserving authentic electronic records into perpetuity. College & Research Libraries, 63(5), American Library Association, Chicago, IL. ISSN , Kejser, U.B, Nielsen, A.B., Thirifays, A. Cost Aspects of Ingest and Normalization, Proceedings of the ipres2011 Conference, November 1-4, 2011, Singapore,

8 financial statements. The model should also state how possible financial adjustments, e.g. to account for inflation, are made, and how investments are depreciated. As do most current cost models, the CMDP tool applies activity based costing, 24 and it refers to the International Cost Model Standard. 25 The tool breaks the cost of individual activities down in the effective time required to complete the activity, measured in person-weeks, multiplied by the salary level, plus purchases, i.e. monetary value. It includes all direct expenses from investment, operation and maintenance, but it does not yet account for indirect costs (overhead). Depending on what type of cost analysis is needed, all investment costs can be depreciated linearly over their useful lifetime or they can be accounted for in the year that they fall due. The CMDP tool applies three salary levels, which are: manager, computer scientist, and technician. As all constants in the CMDP tool the actual salary levels can be individually adjusted to account for specific cases. Predictions of preservation costs beyond just a few years are highly uncertain increasing exponentially over the years. This uncertainty is especially due to the difficulty of predicting future costs of technology. Future costs estimates can be based on projecting historic cost data and either assuming status quo or an increase or decrease in costs. However, uncontrollable incidents may occur that radically change the former course of the costs. For example, the cost of storage media per capacity has decreased over the last decades, but the flooding catastrophe in 2010 in Thailand, suddenly made prices increase significantly on the short term. Likewise, economic crises, such as in 2008, are likely to influence the rate of increase in costs of e.g. salaries. In addition, conflicting tendencies ad to the uncertainty, e.g. on the one hand formats tend to become more complex, which, if all else is equal, will increase the costs of managing them; on the other hand, it has also been argued that formats tend to become more stable, decreasing the needed migration frequency in a migration strategy, and thus the costs. Currently the CMDP tool does not account for financial adjustments. Ideally these should be included, but with a view to the overall uncertainty of the cost projections, this has not yet been given priority. Due to the lack of more accurate estimates, the CMDP tool assumes that costs remain status quo. 2.9 Cost drivers The total costs of preserving assets are comprised of fixed costs and variable costs. The latter depend on the quantity and quality of assets and the expected duration of preservation, whereas the fixed costs, e.g. salaries, rents and utilities, are relatively independent of these, until a certain productivity level. Thus there are some minimum requirements for operating a repository that must be fulfilled; it must e.g. have facilities, systems and people in place, and these fixed costs can provide for a certain production of assets. If the repository does not exploit its capacity, the costs per assets are higher than if it operated at full capacity. The quantity of assets to be preserved and their size (data volume) is obviously an important driver of costs, and especially storage costs 26. In the CMDP tool quantity is accounted for by the annual increase in the amount of data (GB) to be preserved over the costing period. It is not yet possible to also enter the 24 Cooper, R., Kaplan, R.S., Maisel, L.S., Morrissey, E. & Oehm, R.M., Implementing Activity-Based Cost Management: Moving from Analysis to Action,New Jersey. Montvale, Institute of Management Accountants, OECD, International Standard Cost Model Manual to reduce administrative burdens, 2004, accessed August 2012, 26 Nielsen, A.B., Thirifays, A., Kejser, U.B, Costs of Archival Storage, Proceedings of the Archiving 2012 Conference, 2012,

9 number of assets, which can in some cases counter that large files are disproportionately more expensive than small files. A generic cost model must enable accounting for the quality of the preserved assets. The quality of the assets, including the type of format and how they are preserved, influences the preservation costs at different levels: From the lowest level representing the quality of the individual preservation activities, to the quality of groups of activities to the quality of the whole preservation lifecycle. The quality of the format, e.g. it s complexity and whether it is compressed or not, may influence the data volume, and thus the storage costs, but it may also affect the cost of managing the assets over time; all things being equal, simple formats preserved by the migration strategy tend to be less expensive to manage over time than more complex formats. One of the most important cost drivers here is the migration frequency and thus the expected longevity of formats. In the end the overall quality of the preservation activities defines the value that the assets accrue for stakeholders. In the CMDP tool quality is only accounted for implicitly by the selections that users of the cost tool make when inputting data. Thus, the quality of the information security is e.g. partly defined by the selected number of instances (copies) of each asset and by the selected types of preservation systems, e.g. based on optical or magnetic media storage media, on-line, near-line or off-line solutions. Likewise, the quality of the assets is partly defined by the selected types of formats and their ability to preserve significant properties. Currently, the CMDP tool assumes the use of the migration strategy with normalisation at ingest. It is possible to select the type of production format from a list and, if required, the tool also suggests suitable preservation formats. The tool can also account for the cost of ingesting the assets in their original format and keeping them status quo for a future emulation. However, it cannot estimate for the future costs of emulation tools to make the assets accessible if the original format has become obsolete. The tool predicts the longevity of the formats individually, but these predefined values can be changed. The perceived duration of preservation is also a significant factor in cost assessment. The CMDP tool allows users to estimate cost over 20 years. In relation to the before mentioned difficulties in projecting cost, this is of course a very uncertain prediction. However, such estimates may still be of use because they show tendencies in cost projections and indicate when important costs are expected to fall due. 3. Discussion One may ask if it is realistic to aim for a generic cost model capable of accounting for all possible preservation scenarios and use cases, including budgeting, optimisation, and comparing alternatives. Based on experiences from the CMDP project it seems possible to design a generic cost model for as long as the model is kept at a sufficiently conceptual level. The challenges rise however, on implementing the general principles in a tool that can make the actual cost assessments. Creating cost profiles for specific scenarios may be a way to meet this challenge. The profiles should include contextual descriptions of the nature of the assets and the organisation responsible for preserving the assets, and of the resulting requirements for the quality of the assets. Archival storage represents the least complex and most mature area within the digital preservation lifecycle. It has received considerable attention with regards to cost modelling and it is the area from which most empirical cost data is available. Therefore, the developers of a generic cost model would 9

10 likely benefit from using archival storage as the first area to develop, and then use the achieved results to leverage the remaining areas of the lifecycle. Defining a common terminology related to costs and benefits of preserving digital assets is an important prerequisite for agreeing on requirements for a conceptual cost model. The terminology provided by the OAIS standard and other vocabularies developed within the digital preservation community constitute a good basis, but they need to be extended with definitions of economic concepts and a business-oriented vocabulary. The OAIS functional model provides a sound basis for accounting for cost of preserving digital assets, since it describes all major functions in digital preservation. Furthermore, it is already used for benchmarking organisations, e.g. in relation to audit and certification. 27 Cost models based on OAIS are structured accordingly, and other cost perspectives may be required, e.g. ones oriented at specific business processes. 28 However, if the cost methodology is sufficiently detailed and well-documented, it should be possible to assemble the activities deducted from the OAIS functional descriptions in groups that allow for analysing other specific processes. The complexity of the digital preservation landscape entails very detailed cost models that are difficult to understand and use by anyone other than their own designers; on the other hand simpler models are often not accurate and precise enough to provide the required cost data. Thus there is a need for addressing the challenge between the complexity of the models and their user-friendliness. One of the most difficult things in cost modelling is to identify and account for cost drivers. Especially, it is not straightforward to model how the various aspects of quality of the preserved assets influence costs. Initial work has been done to express certain quality aspects of information security mathematically, 29 but so far quality can only be accounted for in relatively subjective terms. At a high level, one way forward in benchmarking the quality of the assets could be to associate the costs of preservation with the certification rakings obtained by a repository through audit. Assessment of quality is further complicated by the fact that the perceived value of a certain quality aspect is not an absolute measure, but dependent on the benefits that it represents to specific stakeholders. Thus, there is a need for combining cost models with benefit and business models to account for other economic factors. 4. Conclusion Preservation cost data constitutes an important source for managing repositories, and cost data is required for various purposes including budgeting, optimisation, and evaluation of alternative preservation opportunities. They are also essential for the assessment of the value of the preserved assets and thereby stakeholders willingness to pay for this value. The increasing amount of digital information to be preserved underlines the need for optimising the cost-efficiency of preservation activities and reaching best practices within the community. This requires complete and consistently collected cost data, which can be achieved through the use of a generic cost model. 27 ISO 16363:2012, Space data and information transfer systems -- Audit and certification of trustworthy digital repositories, COBIT 5: A Business Framework for the Governance and Management of Enterprise IT, accessed August 2012, 29 Zierau, E., Kejser, U. B., Kulovits, H.: Evaluation of Bit Preservation Strategies, In: Proceedings of the 7th International Conference on Preservation of Digital Objects (ipres), Vienna, Austria, pp , 2010, accessed August 2012, 10

11 Developers of cost models should therefore cooperate to develop a generic cost model to which profiles for specific preservation scenarios could be applied. Having created such a common framework it will be possible and necessary to have well-documented cost data to test and improve the coverage and precision of existing models and tools. However, this is hard task since digital preservation is not yet a mature business with a best practice. In order to allow for comparing the costs of preserving assets for different organisations it is also important to account for the quality related to the preserved assets and the value that it represent to stakeholders. Therefore, it is important to link cost models with economic models to represent both cost and benefits of preserving access to digital assets. Acknowledgements We wish to thank the Danish Ministry of Culture, The Danish National Archives and Royal Library for their support of the CMDP project. 11