Samenvatting
It one starts from a well-understood and well tabulated distribution, it is easy to calculate the percentage points of a transformed distribution, but it may not be easy to calculate its moments. Purpose of this article is to discuss some general approximations which give approximate means and standard deviations. First purpose is to explore the constancy of such instances for a variety of frequency curves. Examined is the behaviour of K. Pearson's system of frequency curves. The investigation is, except for some comparisons, limited to percentage points which have been most commonly tabled.