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Levels of Measurement
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Page 1: Measurement levels

Levels of Measurement

Page 2: Measurement levels

The Levels of Measurement

Nominal Ordinal Interval Ratio

Page 3: Measurement levels

What Is Level of Measurement?

The relationship of the values that are assigned to the attributes for a variable

Page 4: Measurement levels

What Is Level of Measurement?

The relationship of the values that are assigned to the attributes for a variable

Relationship

Page 5: Measurement levels

What Is Level of Measurement?

The relationship of the values that are assigned to the attributes for a variable

1 2 3

Relationship

Values

Page 6: Measurement levels

Why Is Level of Measurement Important?

Helps you decide what statistical analysis is appropriate on the values that were assigned

Helps you decide how to interpret the data from that variable

Page 7: Measurement levels

Nominal Measurement

The values “name” the attribute uniquely.

Page 8: Measurement levels

Nominal Measurement

The values “name” the attribute uniquely.

The name does not imply any ordering of the cases.

Page 9: Measurement levels

Nominal Measurement

The values “name” the attribute uniquely.

The value does not imply any ordering of the cases, for example, jersey numbers in football.

Page 10: Measurement levels

Nominal Measurement

The values “name” the attribute uniquely.

The value does not imply any ordering of the cases, for example, jersey numbers in football.

Even though player 32 has higher number than player 19, you can’t say from the data that he’s greater than or more than the other.

Page 11: Measurement levels

Ordinal Measurement

When attributes can be rank-ordered…

Page 12: Measurement levels

Ordinal Measurement

When attributes can be rank-ordered… Distances between attributes do not

have any meaning.

Page 13: Measurement levels

Ordinal Measurement

When attributes can be rank-ordered… Distances between attributes do not

have any meaning,for example, code Educational Attainment as 0=less than H.S.; 1=some H.S.; 2=H.S. degree; 3=some college; 4=college degree; 5=post college

Page 14: Measurement levels

Ordinal Measurement

When attributes can be rank-ordered… Distances between attributes do not

have any meaning,for example, code Educational Attainment as 0=less than H.S.; 1=some H.S.; 2=H.S. degree; 3=some college; 4=college degree; 5=post college

Is the distance from 0 to 1 the same as 3 to 4?

Page 15: Measurement levels

Interval Measurement

When distance between attributes has meaning…

Page 16: Measurement levels

Interval Measurement

When distance between attributes has meaning, for example, temperature (in Fahrenheit) -- distance from 30-40 is same as distance from 70-80

Page 17: Measurement levels

Interval Measurement

When distance between attributes has meaning, for example, temperature (in Fahrenheit) -- distance from 30-40 is same as distance from 70-80

Note that ratios don’t make any sense -- 80 degrees is not twice as hot as 40 degrees (although the attribute values are).

Page 18: Measurement levels

Ratio Measurement

Has an absolute zero that is meaningful

Page 19: Measurement levels

Ratio Measurement

Has an absolute zero that is meaningful Can construct a meaningful ratio

(fraction)

Page 20: Measurement levels

Ratio Measurement

Has an absolute zero that is meaningful Can construct a meaningful ratio

(fraction), for example, number of clients in past six months

Page 21: Measurement levels

Ratio Measurement

Has an absolute zero that is meaningful Can construct a meaningful ratio

(fraction), for example, number of clients in past six months

It is meaningful to say that “...we had twice as many clients in this period as we did in the previous six months.

Page 22: Measurement levels

The Hierarchy of Levels

Nominal

Page 23: Measurement levels

The Hierarchy of Levels

Nominal Attributes are only named; weakest

Page 24: Measurement levels

The Hierarchy of Levels

Nominal Attributes are only named; weakest

Ordinal

Page 25: Measurement levels

The Hierarchy of Levels

Nominal Attributes are only named; weakest

Attributes can be orderedOrdinal

Page 26: Measurement levels

The Hierarchy of Levels

Nominal

Interval

Attributes are only named; weakest

Attributes can be orderedOrdinal

Page 27: Measurement levels

The Hierarchy of Levels

Nominal

Interval

Attributes are only named; weakest

Attributes can be ordered

Distance is meaningful

Ordinal

Page 28: Measurement levels

The Hierarchy of Levels

Nominal

Interval

Ratio

Attributes are only named; weakest

Attributes can be ordered

Distance is meaningful

Ordinal

Page 29: Measurement levels

The Hierarchy of Levels

Nominal

Interval

Ratio

Attributes are only named; weakest

Attributes can be ordered

Distance is meaningful

Absolute zero

Ordinal