Type of bias whereby a specific kind of subject is systematically excluded from the

study, and thus not represented in the results. May result in both over- and underestimation

of mortality.

Summarizes a hypothesis or group of hypotheses that have been supported with

repeated testing. If enough evidence accumulates to support a hypothesis, it moves to

the next step - known as a theory - in the scientific method and becomes accepted as

a valid explanation of a phenomenon.

The initial building block in the scientific method. Many describe it as an “educated

guess”, based on prior knowledge and observation, as to the cause of a particular

phenomenon. It is a suggested solution for an unexplained occurrence that does not fit

into current accepted scientific theory. A hypothesis is the inkling of an idea that can

become a theory, which is the next step in the scientific method.

An account or synopsis of a possible course of events that could occur, which forms

the basis for planning assumptions (for example, a river floods, covering a nearby town

and wiping out the local population's crop). Scenario-building is process of developing

hypothetical scenarios in the context of a contingency planning exercise.(1)

(1) Inter-Agency Contingency Planning Guidelines for Humanitarian Assistance 2001.