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Reliability refers to the consistency of
results when the screening program is repeated on the same persons under the same
conditions. The clear definition of the endpoint and the standardization of screening
methods should be respected to avoid any possible variation in results. The possible
causes of variation in results when repeated screening is performed could reside in the
biological variation of the actual manifestation being measured such as blood pressure
which varies considerably for a given individual with time and under various
circumstances. Also, the precision of the instrument used could result in varying results
as the standard mercury sphygmomanometer for blood pressure. Variability may also occur
from differences in repeated measurements from the same screener or inconsistencies
attributed to differences in the way different screeners apply or interpret the screening
program results. |