to avoid the variety in subjective (ambiguous) interpretation of quantifying terms such as "green", "hot", "large", "considerable", and "negligible", scientists try hard, where possible, to eliminate human senses by use of standardized measuring tools (meter stick, stopwatch, thermometer, etc.) and mechanical/electronic measuring instruments (spectrometer, voltmeter, timer, oscilloscope, gravimeter, etc.) for performing the actual measuring process, eliminating much of the perceptive variability of individual observers. the results of measurements are expressed on a numerical scale of standard units - so that everybody else understands them the same way. where data must need be used, the ideal is to use "hard", "objective" criteria for assigning the classifications (see definition), such that different classifiers would get the same results.