The assessment tool must elicit accurate information on the types of physical activities that encompass the greatest proportion of energy expenditure in the study population. If not, the assessment tool will fall short and lead to an inaccurate assessment.

Accuracy is the degree to which an assessment tool is able to measure physical activity and/or exercise. Accuracy is comprised of both validity and reliability.

•Validity is the degree to which an instrument measures what it sets out to measure.

•Reliability of an assessment tool relates to it’s repeatability. Will the results that were obtained with a particular assessment tool be replicated if the test is repeated?

•Sensitivity relates to the ability of an assessment tool to accurately measure and detect change in physical activity patterns.