Interval and ratio scales are similar in that they both allow for categorization, ranking, and equal spacing between adjacent values. In other words, you can determine which values are higher or lower than others, and you can quantify the difference between them.
Here's a breakdown of their similarities:
- Categorization: Both types of data can be grouped into meaningful categories.
- Ranking: Data points can be ordered or ranked from lowest to highest.
- Equal Intervals: The difference between two values is meaningful and consistent across the scale. For example, the difference between 10 and 20 is the same as the difference between 20 and 30 on both interval and ratio scales.
| Feature | Interval Scale | Ratio Scale |
|---|---|---|
| Categorization | Yes | Yes |
| Ranking | Yes | Yes |
| Equal Intervals | Yes | Yes |
| True Zero | No | Yes |
The key difference lies in the presence of a true zero point. A ratio scale possesses a true zero, indicating the absence of the measured quantity. An interval scale, however, does not have a true zero. For example, temperature measured in Celsius or Fahrenheit is interval data. A temperature of 0°C does not mean there is no temperature; it is simply a point on the scale. Height, weight, and age are examples of ratio data because zero truly means the absence of height, weight, or age.
