Numerical data
Numerical data, also known as quantitative data, is data that is presented in numbers and can be measured.
Continuous Data: Can take any value within a range. For example, height (175.5 cm), weight (70.2 kg).
Discrete Data: Can only take specific, separate values. For example, number of students in a class (30).
Categorical Data
Data that represents categories or groups.
Nominal Data: Categories with no intrinsic order such as eye color (blue, green, brown).
Ordinal Data: Categories with a specific order. For example, movie ratings (poor, fair, good, excellent)
Interval Data
Interval data is a type of quantitative data that is measured along a scale, where each point is placed at an equal distance from one another. However, interval data does not have a true zero point. Interval data does not use zero as a reference. For example, the difference between 20°C and 30°C is the same as between 30°C and 40°C. However, 0°C does not mean the absence of temperature; it is simply a point on the scale. Time is an example of interval data. Interval data is a type of quantitative data that uses an ordered scale to group variables into categories. Each value is separated from the other by an equal distance, and the distances between values are called intervals.
Ratio Data
Ratio data is another type of quantitative data that has all the properties of interval data, but with a meaningful zero point. This means that zero represents the complete absence of the quantity being measured, allowing for the full range of mathematical operations, including multiplication and division. For example, height measured in centimeters or inches, a height of zero indicates no height, and you can meaningfully say that one person is twice as tall as another.
Some more examples – Blood pressure readings (numeric/continuous), number of patients visiting a clinic each day (numeric/discrete), types of diseases (categorical/nominal), stages of cancer (categorical/ordinal), temperature readings in celcius (interval), dosage of medication in milligrams (ratio).