Human Design states that its five types are unevenly distributed across the population, and the Projector is usually placed in the middle of that distribution. The claim is more checkable than most in the system.
Why it is checkable
The type is calculated from a birth time by a fixed rule. Given a large enough set of birth times, the frequency of each type in that set can be computed exactly, with no interpretation involved at any step. Proportions quoted in the literature vary between sources, and this atlas does not repeat a figure it could not verify.
What can be said is that the distribution is a mathematical consequence of the calculation and of the distribution of birth times, and that it is therefore a fact rather than a doctrine. Any two people who compute it correctly from the same data will agree.
What is not checkable in the same way
The claim that people of this type function better under one approach than another is of a different kind. It is stated by the system and is not established by any independent published test.
Provenance
The typology is not inherited. Neither the I Ching, nor astrology, nor the chakra model, nor the Tree of Life sorts people into these categories. The five types were introduced by Ra Uru Hu in 1987, and the atlas records them as the system's own model rather than as ancient material or as established fact.