Ratio Measurement Scale and Absolute Zero Levels of measurement are: Nominal, ordinal, interval and ratio.
What happens when the absolute zero of a data set using the ratio scale is a negative number? I.E when the absolute zero is -25,000? How does this impact related math. Or does it?
 A: If you use the absolute scale, for which 'absolute 0' is the $0,$ then
that's a ratio scale.
For example, $0^o$ Kelvin is the same as $-273.15^o$ C. On the Kelvin scale you can make sense of the statement $100^0$ K is half as 'hot' as $200^0$ K. [Half is a ratio.]
In cooking, you couldn't make sense of "$100^0$ C (boiling water) is half as 'hot' as $200^0$ C" (baking bread). 
A: If the absolute zero on your scale is -25,000, by which I presume you mean observing a score of -25,000 implies that there is none of the construct of interest, then you have an interval scale, not a ratio scale. 
A ratio scale is one in which a score of 0 corresponds to having none of the construct, and doubling the score corresponds to doubling the amount of the construct. Counts and amounts are ratio; most other numerical measurements (e.g., IQ score, SAT score, score on visual analog scale, etc.) are interval. If you could shift the entire scale by a constant and the new values would have the same meaning as the old values, then you have an interval scale (e.g., measuring on a scale from -3 to 3 is the same as measuring on a scale from 1 to 7). 
