Ratio level of measurement is the highest and most precise level of measurement. Variables at the ratio level possess all the characteristics of nominal, ordinal, and interval variables but also have a true zero point, where zero represents the complete absence of the variable being measured. In ratio measurement, both the differences between values and the ratios or proportions between values are meaningful and quantifiable.
Key characteristics of ratio variables are:
1. Distinct Categories: Like nominal, ordinal, and interval variables, ratio variables have distinct categories or groups.
2. Order or Ranking: Ratio variables have an inherent order or ranking among the categories, similar to ordinal variables.
3. Equal Intervals: Ratio variables have equal intervals or differences between adjacent categories, similar to interval variables.
4. True Zero: Ratio variables have a true zero point, where zero represents the complete absence of the variable being measured.
Examples of ratio variables include:
• Height: Height measured in centimeters or inches. The intervals between values are equal, and zero represents the absence of height.
• Weight: Weight measured in kilograms or pounds. The intervals between values are equal, and zero represents the absence of weight.
• Time: Time measured in seconds, minutes, hours, etc. The intervals between values are equal, and zero represents the absence of time.
• Income: Income measured in a specific currency. The intervals between values are equal, and zero represents the absence of income.
In statistical analysis, ratio variables can be summarized using measures of central tendency (mean, median) and measures of dispersion (standard deviation). Parametric statistical tests, such as correlation, regression, or t-tests, are commonly used for analyzing ratio data. In addition, ratios or proportions between ratio variables have meaningful interpretations and can be used for comparisons and calculations.
