Changes

Educational Ministries, Inc. 1998</ref>

Educational Ministries, Inc. 1998</ref>

Models can be empirically found, or derived from fundamental laws. A good model has a well-defined domain of validity, in which it leads to unambiguous, self consistent results. Ideally it is easy to evaluate. To adaption of a model to a specific problem instance is done by model parameters, which can be defined/measured independently or left as free parameters to fit the model to a realistic situation. A large number of free parameters makes it difficult to assess the validity of the model without independent knowledge.

Models can be empirically found, or they can be derived from fundamental laws. A good model has a well-defined domain of validity, in which it leads to unambiguous, self-consistent results. Ideally it is easy to evaluate. To adaption of a model to a specific problem instance is done by model parameters, which can be defined/measured independently or left as free parameters to fit the model to a realistic situation. A large number of free parameters makes it difficult to assess the validity of the model without independent knowledge.

You can also make a model simply by fiddling around with the data, as NASA did when studying the erosion of O-rings used in the [[space shuttle]]:  

One can also make a model simply by fiddling around with the data, that is, "curve fitting" without a fundamental understanding of the phenomenon, as NASA did when studying the erosion of O-rings used in the [[space shuttle]]:  

 

:A mathematical model was made to calculate erosion. This was a model based not on physical understanding but on empirical curve fitting.<ref>[http://www.ralentz.com/old/space/feynman-report.html Feynman's Appendix to the Rogers Commission Report on the Space Shuttle Challenger Accident]</ref>

:A mathematical model was made to calculate erosion. This was a model based not on physical understanding but on empirical curve fitting.<ref> [http://www.ralentz.com/old/space/feynman-report.html Feynman's Appendix to the Rogers Commission Report on the Space Shuttle Challenger Accident]</ref>

==References==

==References==