# Types of Scales

**It can be only of the following four types:****â€‹**Nominal scale- Ordinal scale
- Interval scale
- Ratio scaleâ€‹

**Nominal scale**

One can identify nominal scale data by recognizing the qualitative categories or groups. It is very simple to identify such data as the information in divided into categories according to some definitive qualitative basis e.g.:- Male/female
- White/black
- Urban/suburban/rural

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**Ordinal scaleâ€‹**- Nominal scale data is just about differentiating statistical data according to nomenclature. But if one categorizes data then it becomes ordinal scale data e.g.:
- Ranking of medical students according to their examination performance in their class.
- Categorization of anemia as
**mild, moderate and severe anemia.**

**â€‹**Ordinal scale data can either be qualitative or quantitative.

- Nominal scale data is just about differentiating statistical data according to nomenclature. But if one categorizes data then it becomes ordinal scale data e.g.:
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**Interval scale****â€‹**If one can place the ordinal scale data (i.e. data in some meaningful order) with some**meaningful interval**between each successive data entry, it becomes an interval scale data.- e.g.: Measurement of temperature on Celsius scale. In this case the interval (difference) between 90Â° and 80Â° is the same as the interval (difference) between 40Â° and 30Â°.
- Interval scale data is usually of terms, which can be measured, in finite terms. So it is a quantitative data rather than qualitative like nominal data.

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**Ratio scale**

If one can place interval scale data with some meaningful ratio between it, it become ratio scale data, this type of data is bio medically most significant because most of the biomedical variables from a ratio scale i.e. have an absolute zero e.g.- Weight (grams/kg/pounds)
- Time (seconds/minutes)
- Blood pressure (mmHg)
- Pulse rate (beats per minute)â€‹