0‘quv materiallari (ma’ruza matni)

the influence of a single parameter, with
some other conditions kept unrealistically constant.
Sometimes it is forgotten that, in a concrete
mix, it is usually not possible to change one ingredient
without altering some other property of
the mix.
Generalized inferences from such piecemeal research are at best difficult and at worst dangerous.
We do not need more of these little research projects, each one chalking up a ‘publication’ in the author’s curriculum vitae. Nor do we need an endless succession of formulae, each derived from a small set of data. Some, seemingly impressive, analyses show an excellent correlation with the experimental data fed into the pool from which the expressions were derived in the first place: such correlation is not surprising. But then it should not be surprising either if the expressions fail dismally when used to predict the behaviour in untried circumstances where there exist factors ignored in the original analysis.
A further comment can be made about the influences
of various factors on the behaviour of
concrete which have been determined by statistical
analyses. While the use of statistics in the