* Interval Level: This level allows for ordering and equal intervals between measurements. However, it lacks a true zero point. For example, think of Celsius temperature. 0 degrees Celsius doesn't mean there is no heat; it's just a reference point. You can add or subtract temperatures, but you can't make meaningful ratios.
* Ratio Level: This level has all the properties of the interval level plus a true zero point. A zero value means the absence of the measured quantity.
Why Fahrenheit is Ratio Level:
* True Zero: Zero degrees Fahrenheit does represent the absence of heat (absolute zero).
* Meaningful Ratios: Because of the true zero, you can make meaningful ratios. For instance, 40 degrees Fahrenheit is twice as hot as 20 degrees Fahrenheit.
In summary: While Fahrenheit allows for ordering and equal intervals, its true zero point elevates it to the Ratio level of measurement.
