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Information is a quality of a message a sender to one or more receivers. Information
is always about something (size of a parameter, occurrence of an event, ...).
Viewed in this manner, information does not have to be accurate. It may be a
truth or a lie, or just the sound of a kiss. Even a disruptive noise used to
inhibit the flow of communication and create misunderstanding would in this view
be a form of information. However, generally speaking, if the amount of information
in the received message increases the more accurate the message is.
This model assumes there
is a definite sender and at least one receiver. Many refinements of the model
assume the existence of a common language understood
by the sender and at least one of the receivers. An important variation identifies
information as that which would be communicated by a message if it were sent
from a sender to a receiver capable of understanding the message. However,
in requiring the existence of a definite sender, the "information as a
message" model does not attach any significance to the idea that information
is something that can be extracted from an environment, e.g., through observation,
reading or measurement.
Information is a term with many meanings depending on context, but is as a
rule closely related to such concepts as meaning, knowledge, instruction, communication,
representation, and mental stimulus. Simply stated, Information is a message
received and understood. In terms of data, it can be defined as a collection
of facts from which conclusions may be drawn. There are many other aspects
of information since it is the knowledge acquired through study or experience
or instruction. But overall, information is the result of processing, manipulating
and organizing data in a way that adds to the knowledge of the person receiving
it.
Communication theory is
a numerical measure of the uncertainty of an outcome, for example, we can
say that "the signal contained thousands of bits of
information". Communication theory tends to use the concept of information
entropy, generally attributed to C.E. Shannon (see below).
Another form of information is the Fisher information, a concept of R.A. Fisher.
This is used in application of statistics to estimation theory and to science
in general. Fisher information is thought of as the amount of information that
a message carries about an unobservable parameter. It can be computed from
knowledge of the likelihood function defining the system. For example, with
a normal likelihood function, the Fisher information is the reciprocal of the
variance of the law. In the absence of knowledge of the likelihood law, the
Fisher information may be computed from normally distributed score data as
the reciprocal of their second moment.
Even though information and data are often used interchangeably, they are
actually very different. Data is a set of unrelated information, and as such
is of no use until it is properly evaluated. Upon evaluation, once there is
some significant relation between data, and they show some relevance, then
it is converted into information. Now this same data can be used for different
purposes. Thus, till the data convey some information, they are not useful.
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