It is now widely recognized that appropriate measures are required for digital preservation to ensure that digital data can be accessed and used currently and in the future. Among all the risks of digital preservation

format obsolescence is one of the most important. There have been several projects or initiatives dealing with the measurement method of format obsolescence risk

but there has been no mechanism to quantify the preservation risk or durability of digital formats based on a self-improving assessment model

executed with the aid of computers. This paper deals with a methodology for measuring the preservation durability of digital formats

especially for their risk assessment. This method is based on a quantitative assessment model for format risk

and can shift the non-quantifiable knowledge or experiences of field experts to a machine identifiable and processible form

or ‘risk scores’. Results can be recognized and communicated by computers automatically and formally

which can assist in the automatic/semi-automatic risk management for digital preservation

sharing this quantified knowledge among communities. Because technologies are changing quickly

the quantitative assessment model for risks will not be a status quo situation. Thus

also presented is a method to fine tune the quantitative assessment model for risk of formats through a self-learning and self-improving style.