In order to perform an evaluation, it is necessary that the data or information collected be:

The requirement for data or information to be valid and reliable is crucial for conducting an evaluation. Validity refers to the degree to which the information accurately reflects the concept or phenomenon being studied. For example, if an evaluation is assessing the effectiveness of an environmental health intervention, the data collected must directly measure the outcomes related to that intervention. Reliability pertains to the consistency and dependability of the data over time; if the same measurement is taken multiple times under similar conditions, reliable data should yield the same results.

When data is both valid and reliable, it ensures that the evaluation is based on sound evidence. This foundation allows for accurate conclusions and recommendations, leading to effective decision-making in environmental health practices. Without validity, the conclusions drawn could be misleading, and without reliability, a change in study conditions could produce different results, undermining the evaluation's credibility.

While factors like being current, organized, understandable, or unbiased are important, they do not directly address the foundational integrity of the data in assessing its effectiveness for an evaluation. Validity and reliability are fundamental to ensure that the evaluation is meaningful and accurately reflects the situation being addressed.