Measurement outside the laboratory

The kinds of models discussed in this paper function as measuring instruments. We will concentrate on two necessary steps for measurement: (1) one should search for a mathematical representation of the phenomenon; (2) this representation about the phenomenon should cover an invariant relationship between properties of the phenomenon to be measured and observable associated attributes of a measuring instrument. Therefore, the measuring instrument should function as a nomological machine. However, invariant relationships are not necessarily ceteris paribus regularities, but could also occur when the influence of the environment is negligible. Then we are able to achieve accurate measurements outside the laboratory.