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Basics of Research Process

# 4 Levels of Measurement in Research: Nominal, Ordinal, Interval & Ratio Worried about writing a unique paper? Use our free

Levels of measurement are the types of scales or categories that are used to measure and quantify data. There are four levels of measurement: nominal, ordinal, interval and ratio. The level of measurement can influence the choice of statistical methods used to analyze the data, as some methods may be more appropriate for certain types of data than others.

If you are dealing with quantitative analysis, first, you should find out what levels of measurements are in statistics (or scale assessments in some sources). It is important to choose a right scale assessment in research. This will provide an opportunity to explore the data correctly and obtain high-quality results. The four most common levels of measurement are nominal, ordinal, interval, and ratio, each of which provides unique information and requires different statistical analysis techniques.

If you do not know what ordinal, nominal, interval, and ratio measurements are, then this blog is for you!  Further in the article, you can find answers to your questions and figure out what research level of measurement is suitable for your study.

## What Are Levels of Measurement?

So, what’s the main trick with levels of measurement? In simpler terms, this is a classification that describes information within variables. Levels of measurement are different ways of measuring and grouping data in research. Generally, there are 4 levels of measurement that are usually used for various types of research designs. We are talking about nominal, ordinal, interval, and ratio levels of measurement.

Thanks to them, it becomes possible to identify vital characteristics of certain objects or events. This makes it easy to analyze data and establish connections and ratios of variables. It is also vital to understand that different levels refer to different types of information, depending on the amount of data available and the nature of the analysis tools.

## Why Are Levels of Measurement Significant?

So, why levels of measurement in research matter? In a nutshell, they allow researchers to determine how a certain data level can be analyzed. The significance of data measurement levels can be summarized in the following list:

• Specifies the type of statistical analysis Level of variable measurement determines the type of statistical analysis that can be performed on the data.
• Ability to influence the depth and nature of understanding The data level of measurement impacts the insights that can be gained from the data.
• Reliability of statistical tests Scale assessment has an impact on reliability. Therefore, it is the correct choice of level that can guarantee reliability.
• Ability to define how data is visualized For example, it can be visualized using bar charts for nominal data or histograms for intervals.

## 4 Levels of Measurement in Research

As mentioned earlier, 4 levels of measurement for variables are used that allow researchers to collect data and describe it. So, here are 4 levels of measurement in statistics:

1. Nominal level This scale assessment is used to separate data into different groups based on one or more qualitative characteristics. Examples of a nominal data level include gender or eye color.
2. Ordinal level This level implies the ranking of data in a specific sequence or order. There are no equal intervals between the values, but they can be arranged in a meaningful order. For example, this can be a rating of academic performance or competitions.
3. Interval level Interval measurement scales are used to measure variables  where the intervals between values are equal. This measuring level does not have a true or absolute zero point. Examples of interval data include temperature or time.
4. Ratio level The ratio scale assessment equals the interval level but has a true zero point. There must be a significant absence of the measured variable.

## Nominal, Ordinal, Interval and Ratio Data Levels Explained & Examples

What are nominal, ordinal, interval, and ratio level examples? Below you can find more details about each scale assessment as well as examples in order to understand the essence of each more clearly.

### Nominal: The First Measurement Level

It is a categorical data type used to label or name variables without any quantitative value. Each value has a name, symbol, or category used to describe the attribute being measured.

Nominal data is often used in surveys and questionnaires. It is also used in many areas of research, for example, social sciences, psychology, and marketing. Nominal data are usually analyzed using non-parametric tests such as chi-square tests or Fisher's exact tests.

It is vital to understand that there is a limitation of nominal data, namely that it does not provide any information about the order of the values. The data cannot be ranked, making it impossible to determine which category will be larger or smaller.

When it comes to levels of measurement examples of nominal data, this can be gender, race, religion, and marital status. In these cases, each value represents a separate category or label.

Example

For example, in case of gender, there are two categories: men and women. These categories themselves do not convey any quantitative information, but they make it possible to distinguish between different groups. It can work by analogy with hair color when blondes, brunettes, redheads, and brown-haired women or men are distinguished. Therefore, nominal date is often used to categorize variables or classes.

### Ordinal: The Second Measurement Level

Ordinal scale is the second among levels of data measurement in statistics. This is a type of data that can be ranked or ordered, and the disparities between values are not necessarily equal. In ordinal data, values represent a hierarchy or ranking of attributes, but the distance between values is unknown or cannot be measured.

Also, keep in mind that there is a limitation in that they do not provide any information about actual distance or magnitude of the values. This means that it is not possible to perform certain mathematical operations on ordinal data, such as multiplication.

Ordinal data is often analyzed using non-parametric statistical tests. These tests are used to compare groups or to assess the strength between two variables.

Examples of ordinal data include education level, income level, and agreement level in a survey. In these cases, each value represents a separate category or label, but these categories may be ranked or ordered.

Example

For example, when talking about educational level, our categories are high school, bachelor's degree, master's degree, and PhD degree. These categories can be arranged in order of educational level, but the disparity between a high school and a bachelor's degree is not the same as the distinction between a bachelor's degree and a master's degree.

### Interval: The Third Measurement Level

The interval is the third scale assessment in statistics. It is a type of data measurement scale that can be ranked or ordered, and the disparities between the values are known and can be measured. In interval data, values are a fixed interval or scale, and the distance between values is constant.

Interval data is often analyzed using parametric statistical tests such as t-tests. Such tests are used to compare groups or to assess the relationship between independent and dependent variables.

Note that interval data has a meaningful zero point. However, zero point does not necessarily mean an absence of a measure. For example, a temperature of 0°C does not mean that there is no heat. This means that it is not possible to perform certain mathematical operations on interval data, such as division.

Example

Examples of interval data include temperature measured in Celsius or Fahrenheit, time measured in hours or minutes, and even IQ scores. In these cases, each value represents a separate value, and the disparities between the values are known and can be measured. You can also measure dates in terms of days, weeks, and months.

As you can see, these examples mean more accurate data that can be compared and allow researchers to perform a wide range of statistical analyses.

### Ratio: The Fourth Measurement Level

The last scale assessment is the ratio scale. This is the fourth and highest scale assessment in statistics. It is a type of data that can be ranked or ordered, and the disparities between the values are known and can be measured. In addition, these ratios have a significant zero point. This means that all mathematical operations can be performed on ratio data.

Ratio data is often analyzed using parametric statistical tests such as regression or correlation analysis. These tests are used to study the relationship between variables or to predict future outcomes.

One of the key features of ratio data is that it allows researchers to create meaningful comparisons between values. For example, a person weighing 90 kg is twice as heavy as a person weighing 45 kg.

Ratio data plays a role in many areas, including science, technology, and business. Its ability to create meaningful comparisons and mathematical operations makes it a valuable tool for analysis and decision-making.

Example

Examples of ratio data include height, weight, distance, and time. In these cases, each value represents a separate value, and the disparities between values are known and can be measured. In addition, there is a meaningful zero point, which represents the absence of a measure. For example, a weight of 0 kg or 0 lb means no weight, while 0 on a thermometer does not mean no temperature.

## How to Determine the Measurement Level of the Variable?

The variable measurement is a crucial step in statistical analysis because it determines which statistical tests can be used on data. Here are some steps how to determine the level of measurement of the variable:

Determining the Measurement Level

 Level Criteria for determining Examples Nominal level When a variable consists of categories or labels that cannot be ranked or ordered, then it is at the nominal level. Gender, race, skin color Ordinal level When a variable can be ranked or ordered, but the disparities between the values cannot be measured or do not make sense, then it is at the ordinal scale assessment. Education level, socioeconomic status, academic ratings Interval level If a variable can be ranked or ordered, and the disparities between values are known and significant, but there is no significant zero point, then it is at an interval level of measurement. Temperature, IQ scores Ratio level When a variable can be ranked or ordered, the disparities between values are known and significant, and there is a significant zero point, then it is at a ratio scale assessment. Height, weight, distance, time

Scale assessment of a variable depends on its nature. After determining it, researchers can select statistical tests as well as data analysis methods.

Nominal vs Ordinal Level Example

What distinguishes nominal and ordinal measurement? Let's imagine a situation where you need to conduct a survey to get data on people's favorite colors. Let's assume possible answers are: pink, blue, green, red, yellow. In this case, the “favorite color” is the nominal level because the categories or labels cannot be ranked or ordered. Each answer is simply a separate category or label. As you understand, there is no internal order or ranking for them.

Now let's look at another example. Suppose you conduct a survey asking people to rate their satisfaction with a product on a scale of 1 to 5, where 1 represents "very dissatisfied" and 5 represents "very satisfied". The responses would be ordinal data, where the values have a natural order or ranking, and the distance between each value is not necessarily equal. In this case, the data can be ranked from 1 to 5 based on the satisfaction rating, and we know that a rating of 5 is higher than a rating of 3, but we cannot say that a rating of 5 is twice as good as a rating of 2.

## Nominal vs Ordinal vs Interval vs Ratio: Key Differences

What are some disparities between nominal, ordinal, interval and ratio scales? These are the nature of values, an ability to rank or order values, significance of disparities between values, and presence of a significant zero point. These differences matter because they determine which statistical tests and methods can be used for your research. This is how you can draw a line between these 4 types of scale assessments.

Check out our comparison chart of operations and measures regarding nominal, ordinal, interval or ratio levels.

Nominal, Ordinal, Interval, or Ratio Comparison Chart

 Operations and measures Nominal Ordinal Interval Ratio Equality ✅ ✅ ✅ ✅ Comparison ❌ ✅ ✅ ✅ Addition and subtraction ❌ ❌ ✅ ✅ Multiplication and division ❌ ❌ ✅ ✅ Absolute zero ❌ ❌ ✅ ✅ Mode ✅ ✅ ✅ ✅ Median ❌ ✅ ✅ ✅ Arithmetic mean ❌ ✅ ✅ ✅ Geometric mean ❌ ✅ ✅ ✅ Range ❌ ❌ ✅ ✅ Interquartile range ❌ ❌ ✅ ✅ Standard deviation ❌ ❌ ✅ ✅ Variance ❌ ❌ ✅ ✅

## Bottom Line on Levels of Measurement

Thus, different levels of measurement in statistics open up a lot of opportunities for researchers. As you've noticed,  measurement scales are different ways of measuring and classifying variables. Getting an understanding of measurement level is vital as it determines what to use (tests and methods of analysis). Also, a correct choice of scale assessment plays a key role in the statistical analysis since this is a guarantee of the reliability and validity of the results that will be obtained at the end of the study. Need expert help?

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## FAQ About Nominal, Ordinal, Interval, and Ratio Levels of Measurement

### 1. What is the measurement level in statistics?

A variable level of measurement in statistics refers to the way data is measured or expressed. There are four basic measurement levels, including nominal, ordinal, interval, and ratio. Each of them has its own characteristics, and scale assessment used can influence the types of statistical tests that can be performed and the insights that can be gained from the data.

### 2. What are the four measurement levels?

There are 4 levels of measurement used to classify and describe data:

1. Nominal level: variables consist of categories or labels that cannot be ranked or ordered.
2. Ordinal level: variables can be ranked or ordered and disparities between values are not necessarily equal or significant.
3. Interval level: variables can be ranked or ordered, and the disparities between the values are known and significant, but there is no zero point.
4. Ratio level: variables can be ranked or ordered, disparities between values are known and significant, and there is a significant zero point.

### 3. How do I determine which measurement level to use?

Determining which level of measurement for variables to pick depends on the type of data being collected and the research question being asked. To figure out how a variable is measured,  you have to consider the nature of your research, its purpose, and the type of data you will be collecting. Therefore, it is worth returning to the basis of each scale assessment.

### 4. What is the difference between nominal and ordinal measurement levels?

The main difference between these two levels of measurement of variables is that nominal data is categorical and cannot be ranked or ordered. In case of ordinal data, the data may be ranked or ordered, but the differences between the values are not necessarily equal. Nominal data is used for variables without quantitative values, while ordinal data is used for variables that have a natural order or ranking.

Article posted on:May 5, 2023
Article updated on:May 5, 2023