Dictionary of Evidence-based Medicine.pdf

Dictionary of Evidence-based Medicine 55
Equivalence studies
Equivalence studies are aimed at demonstrating that two treatments or
formulations are equivalent either in efficacy or bioavailability (see Bioequivalence
studies). For example, if a manufacturer plans to introduce a
new formulation of an existing drug produced by another manufacturer,
drug licensing authorities require evidence that it is bioequivalent to the
existing product (i.e. has the same bioavailability). Otherwise, evidence
of equivalent clinical effects, which is much more expensive to generate,
has to be provided. For a new drug, however, as opposed to a new formulation,
many manufacturers undertake equivalence studies to show that
the product is as effective as an existing drug. They then justify the
introduction of the new drug on the basis of greater safety or lower cost.
Estimator
An estimator is a function of observable random variables, used to
estimate a parameter. The sample mean (*), which is a function of sample
observations, for example, can be used as an estimator of the population
mean (/j). An estimator is said to be unbiased if its expected value is equal
to the parameter being estimated.
European Free Trade Association (EFTA)
With the signing of the Treaty of Rome in 1957, Belgium, France, West Germany,
Italy, Luxembourg and The Netherlands established the European
Economic Community (EEC). Several countries, including Britain, which
were part of the early negotiations, while supportive of intra-European
trade, were unhappy about the establishment of the pan-European administrative
structures which formation of the EEC led to. As a result, those
non-EEC countries, including the Scandinavian countries, Portugal, Switzerland,
Austria and Britain, formed the European Free Trade Association
(EFTA) in 1960 which would abolish tariffs on mutual trade but would
allow each partner to determine its own tariff on trade with non-partner
countries. Soon after, the UK applied for membership of the EEC. In 1973
Britain formally joined the EEC along with Ireland and Denmark.
European Union
The European Union is an association of 12 European states working as
an economic union which, in addition to forming a common market, is
committed to harmonization of their general economic, legal and social
policies. One of the aims of the European Union under the Treaty of