The evaluation process must be impartial and independent. According to the OECD (1991), impartiality contributes to the credibility of the evaluation and to avoid bias in the results, analyses, and conclusions. Independence, on the other hand, provides legitimacy to the assessment and reduces the potential for conflict of interest that could arise if policy makers and managers were solely responsible for assessing their own activities
On the other hand, to influence decision-making, the results of the evaluation must be relevant and useful. Also, evaluations should be timely in the sense of being available at the right time for the decision-making process.