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1.7 Glossary of Terms
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Statistics :
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Statistics is the use of data to
help the decision maker to reach better decisions.
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Data :
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It is any group of measurements
that interests us. These measurements provide information
for the decision maker. (I) The data that reflects non-numerical
features or qualities of the experimental units, is
known as qualitative data. (ii) The data that possesses
numerical properties is known as quantitative data.
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Population:
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Any well defined set of objects
about which a statistical enquiry is being made is called
a population or universe.
The
total number of objects (individuals) in a population
is known as the size of the population. This may be
finite or infinite.
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| Individual : |
Each object belonging
to a population is called as an individual of the population.
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Sample:
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A finite set of objects drawn from the population
with a particular aim, is called a sample.
The total number of
individuals in a sample is called the sample size.
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Characteristic:
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The information required from an individual,
from a population or from a sample, during the statistical enquiry
(survey) is known as the characteristic of the individual. It
is either numerical or non-numerical. For e.g. the size of shoes
is a numerical characteristic which refers to a quantity, whereas
the mother tongue of a person is a non-numerical characteristic
which refers to a quality. Thus we have quantitative and qualitative
types of characteristics. |
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Variate:
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A quantitative characteristic of an individual
which can be expressed numerically is called a variate or a
variable. It may take different values at different times, places
or situations. |
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Attribute:
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A qualitative characteristic of an individual
which can be expressed numerically is called an attribute. For
e.g. the mother-tongue of a person, the color of eyes or the
color of hair of a person etc. |
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Discrete
variate :
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A variable that is not capable of assuming all
the values in a given range is a discrete variate. |
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Continuous
Variate :
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A variate that is capable of assuming all the
numerical values in a given range, is called a continuous variate.
Consider two examples carefully, viz. the number of students
of a class and their heights. Both variates differ slightly,
in the sense that, the number of students present in a class
is a number say between 0 and 50; always a whole number. It
can never be 1.5, 4.33 etc. This type of variate can take only
isolated values and is called a discrete variate. On the other
hand heights ranging from 140 cm to 190 cm can take values like
140.7, 135.8, 185.1 etc. Such a variate is a continuous variate. |
