'''
Created on Mar 22, 2012
@author: steger, jozsef
@summary: Class representation of the measurement levels (aka measurement scale) defined by Stanley Smith Stevens.
Stevens proposed his theory in a 1946 Science article titled "On the theory of scales of measurement".
@note: These classes are not meant to be instantiated ever.
'''
class MeasurementLevel:
'''
@summary: It serves as the common scheme for the measurement levels. Only its subclasses have a meaning.
'''
pass
class Nominal(MeasurementLevel):
'''
@summary: Values of this kind of measurement are mere elements of a set.
'''
pass
class Ordinal(Nominal):
'''
@summary: A ranking is defined between the values of this kind of measurement.
'''
pass
class Interval(Ordinal):
'''
@summary: A difference is defined which can be evaluated for any two values of this kind of measurement.
'''
pass
class Ratio(Interval):
'''
@summary: There is a reference value defined for this kind of measurement, that is "zero" has a meaning.
'''
pass
lut_level = {
'NominalLevel': Nominal,
'OrdinalLevel': Ordinal,
'IntervalLevel': Interval,
'RatioLevel': Ratio,
}