Page 40 - DEDU504_EDUCATIONAL_MEASUREMENT_AND_EVALUATION_ENGLISH

Educational Measurement and Evaluation

Notes 3.5 Interval Scale
This is the third level of measurement. This scale endeavours to do away with the limitations of
the above two scales. Under this scale, we display the difference between any two classes,
individuals or objects by the medium of scores. The distance between two differences is equal.
Lack of exact zero point is a shortcoming of this scale, due to which the measurement done by
this scale is relative measurement, and not absolute; that is, if a student obtains zero marks in
this scale, then it should not be concluded that the student is fully ignorant of the given subject.
Some examples of this scale are thermometer, hour, minute, week month, year etc. In a
thermometer, the normal temperature of an individual is considered at 98.4°F, but if due to
certain reasons, this temperature is read at 97°F, then on the one hand, this shows that that person
has no fever, but it should not be concluded that the individual’s body has no heat or temperature
at all. A thermometer is the most appropriate example of this scale. A thermometer indicates
from 98°F to 108°F. It has the same distance between 98°F and 99°F, so it is between 107°F and
108°F. Under this scale, several statistical calculations can be used, such as mean, percentiles,
standard deviation etc.

Though there is no exact or absolute zero point, in internal scale, still the scores arranged
at equal distances are considered the constant unit of this scale.

3.6 Ratio Scale
This is the highest level of measurement. This scale comprises of all features of all other scales.
The presence of exact or true zero point is the chief feature of this scale. This zero point is not
arbitrary point, rather it is related with the zero amount of certain attribute or feature. In physical
measurement, there is always an absolute zero point, such as meter, km, gram, liter, millimeter
etc. Measurement of height, length, weight or distance is started from zero point. In ratio scale,
the true zero point is considered the initial point of the scale. So, we can find out the ratio
between the distance of any two places, and on its basis, we can say with certainty how distant is
one place from another. Thus, if Rekha, Pinki or Puja are awarded 10, 20 and 40 marks on the
basis of certain attribute, then we will say as per this scale in what measure this attribute exists
in Rekha, and it exists in Pinki in the double measure and in Puja it is four times. It means to say
that each unit in the scale explains different amounts of the attribute, and there is possibility of
applying all basic operations in this scale.

If I.Q of Ram is an intelligence test is 150, and that of Shyam 100, then what is that the
ratio of the intelligence ?

Self Assessment

1. Fill in the blanks :

(i) Nominal scale is also called ______ too.
(ii) Each value on the measurement scale has a ______ meaning.
(iii) The presence of exact or true ______ is the chief feature of the ratio scale.

34 LOVELY PROFESSIONAL UNIVERSITY