Data is qualitative (categorical). Categories, colors, names, labels and favorite foods along with yes or no responses are examples. Nominal scale data are not ordered.
Nominal scale data cannot be used in calculations
Ordinal scale
Data can be ordered. An example is a list of the top five national parks in the United States. Responses like "excellent", "good", "satisfactory", and "unsatisfactory" are ordered from most to least desired.
Ordinal scale data cannot be used in calculations
Interval scale
Data has a definiteordering and the differences between data can be measured, but there is no starting point. Examples are temperature scales like Celsius and Fahrenheit.
Interval level data can be used in calculations, but ratios cannot be calculated
Ratio scale
Data has a 0 point and ratios can be calculated. Examples are exam scores out of 100 points.
