Final answer:
Reliability and validity are two important forms of validity in epidemiological research that must be considered during study design.
Step-by-step explanation:
Reliability and validity are two important forms of validity in epidemiological research that must be considered during study design. Reliability refers to the ability to consistently produce a given result, while validity refers to the extent to which a given instrument or tool accurately measures what it's supposed to measure. In epidemiological research, these forms of validity play a crucial role in ensuring that the data collected is reliable and accurately reflects the phenomena being studied.