Today, the ubiquity of software to reprogram one's engine computer is a reality. However the old adage applies: a little knowledge can be a dangerous thing.
Recently I had the dubious distinction of having to explain to a testy individual about following advice from dubious sources. This person was trying to rescale the MAF resolution by changing the A/D counts and other related parameters by a fixed factor. However he quickly turned defensive when the obvious was pointed out: there was incomplete information as to whether the MAF sensor would still respond with a linear voltage given the increase in mass airflow. Whereupon this person quickly accused me of being disrespectful, discourteous, sarcastic etc. The typical Singaporean knee-jerk response to someone who holds a differing viewpoint. Possibly because he is now charging $140 per tune, whereas the market rate for a professional tune is anywhere from $500 onwards, with $1000 being the average. i.e. monetary interest in appearing to be correct at all times.
A relevant section from John Mandel's "The Statistical Analysis of Experimental Data" is appropriate:
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The methods of statistical analysis are intimately related to the problems of inductive inference: drawing inferences from the particular to the general. R.A. Fisher, one of the founders of the modern science of statistics, has pointed to a basic and most important difference between the results of induction and deduction. In the latter, conclusions based on partial information are always correct, despite the incompleteness of the premises, provided that this partial information itself is correct. For example, the theorem that the sum of the angles of a plane triangle equals to 180 degrees is based on certain postulates of geometry, but it does not necessitate information as to whether the triangle is drawn on paper or on cardboard, or whether it is isosceles or not. If information of this type is subsequently added, it cannot possibly alter the fact expressed by the theorem. On the other hand, inferences drawn by induction from incomplete information may be entirely wrong, even when the information given is entirely correct. For example, if one were given the data of Table 2.1 on the pressure and volume of a fixed mass of gas, one might infer, by induction, that the pressure of a gas is proportional to its volume, a completely erroneous statement.
Table 2.1 Volume-Pressure Relation for Ethylene, an Apparently Proportional Relationship
The error is due, of course, to the fact that another important item of information was omitted, namely that each pair of measurements was obtained at a different temperature, as indicated in Table 2.2. Admittedly this example is artificial and extreme; it was introduced merely to emphasize the basic problem in inductive reasoning: the dependence of inductive inferences not only on the correctness of the data, by also on their completeness. Recognition of the danger of drawing false inferences from incomplete, though correct information has led scientists to a preference for designed experimentation above mere observation of natural phenomena.
Table 2.2 Volume-Pressure-Temperature Relation for Ethylene
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Just as one may be inclined to seek medical information on the Internet, it is still prudent to visit a licensed medical practitioner so that one's ailments may be properly diagnosed and treated. Would you let a "doctor" treat you just because he has read some medical books and charges a low fee?
The age of the amateur is upon us.
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