• To measure or not to measure (and what good is it anyway?)

I am going to take this opportunity to criticize, again, a point that you keep making regarding measurements.

Physical measurements are not a subjective thing and if done correctly are not subject to variations based on the implimenters bias. Now that said, interpretation of the data is more subjective AND making "correct" measurements is not easy. But I take strong exception to your position that someone making their own measurements is invalid and/or not believeable.

If the test setup, technique, equipment, etc. are all described, then I will look at anyones data because the validity can be critiqued from this information (assuming that it is honest and accurate!). I am not a big measurements person (contrary to past posts), I am far more theroetically inclined. Proposing a design - based on theory or models - testing it and finding a high degree of correlation lends a great deal of validity to design concepts. Far more than if the design had not been tested.

Now I am strongly opposed to testing as a means to a design. That does not necessarily ever lead to an optimum - one simply gets tired of testing and says "Well, looks good to me!" Testing should simply be a confirmation of what you expect - you should not see anything unexpected - the results should be completly predictable. If they are not then there is something that is not understood and that aspect needs further investigation until it is understood. The iterative work to the optimum is done with theory (models, math, whatever) and simply confirmed at the end with some measurements.

I'm not going to belabor this issue, but I'd like to make what I think is an obvious point. You wrote:

>> Physical measurements are not a subjective thing and if done
>> correctly are not subject to variations based on the implimenters
>> bias.

The two key things here are "done correctly" and "implementer's bias." There are those that have the inclination but not the ability, either because of lack of equipment or facilities or whatever. And we've also seen people that are eager to make a point throw out datasets unfavorable to the point they want to make. An obvious example is the marketing department of a loudspeaker company making sure their published charts show only their products best features or possibly even exaggerated claims.

Wayne

I'll repeat again - the existance of unscrupulous people is no reason to assume that everyone is that way. Because valid and useful measurements can be made it is prudent to first assume the positive and, at worst, be a little cautious with the unknown experimentor.

There were an awful lot of cars and trucks built between the first internal combustion engine and a comprehensive CFD model of in-cylinder combustion.

The Brooklyn Bridge still stands in daily use today despite the problems in metallurgy with the cables that weren’t even somewhat understood until 50 or more years later.

You really think the pyramids were built on a complete mathematical model? Or that DeForest had it all down pat with the first audion?

The only reason loudspeakers lend themselves to extensive modeling is that they are such simple machines – and even then the level of confusion and disparity of results is breathtaking.