A Comparative Study of Zodiacal Signs on the House Cusps of Quadrant and Equal-sized House Systems
by Kyösti Tarvainen
Astrological house systems come in two main categories: those with equal-sized houses, such as the Equal and Whole Sign House systems, and quadrant house systems, including Placidus and Koch, where house sizes can vary. In equal-sized house systems, the signs on the cusps follow a predictable zodiacal sequence, whereas in quadrant house systems, the sequence may not follow in zodiacal sequence. Consequently, in the latter systems, it’s possible for the same sign to span two or more house cusps, or signs can be intercepted without intersecting a cusp. Some astrology books (Sakoian & Acker, 1973) propose a hybrid approach where planets are placed according to a quadrant house system and the cusps are interpreted in sequential sign order, as happens in the Equal or Whole Sign House systems. Correspondingly, the hypothesis of this research is that the effects of the signs on the cusps of the Equal House and Whole Sign House systems are stronger than that of the signs on the cusp of the Koch or Placidus house systems. In testing 16,552 individuals from the Gauquelin databank, statistically significant confirmation was obtained for this hypothesis with a p-value of .03 supporting Equal or Whole Sign Houses over Placidus Houses and .05 over the Koch House system. However, based on some small surveys, it seems that there are two exceptions: the MC sign might be more potent than the sign on the cusp of the tenth house in the Equal or Whole Sign Houses; similarly, the IC sign may be stronger than the sign on the cusp of the fourth on the Equal or Whole-Sign House Systems. In astrological practice, the houses’ signs determined in the sequential order can also be useful in the rectification of the Ascendant.