But Not Both:The Exclusive Disjunction in Qualitative Comparative Analysis (QCA)

The application of Boolean logic using Qualitative Comparative Analysis (QCA) is becoming more frequent in political science but is still in its relative infancy. Boolean ‘AND’ and ‘OR’ are used to express and simplify combinations of necessary and sufficient conditions. This paper draws out a distinction overlooked by the QCA literature: the difference between inclusive- and exclusive-or (OR and XOR). It demonstrates that many scholars who have used the Boolean OR in fact mean XOR, discusses the implications of this confusion and explains the applications of XOR to QCA. Although XOR can be expressed in terms of OR and AND, explicit use of XOR has several advantages: it mirrors natural language closely, extends our understanding of equifinality and deals with mutually exclusive clusters of sufficiency conditions. XOR deserves explicit treatment within QCA because it emphasizes precisely the values that make QCA attractive to political scientists: contextualization, confounding variables, and multiple and conjunctural causation

Pharmacological Modulation By Cetirizine and Ebastine of the Cutaneous Reactivity To Histamine

The peripheral H-1-inhibition effects of cetirizine 10 mg and ebastine 10 mg were compared at the skin level after single oral administration. The study was performed in 9 healthy subjects under double-blind randomized crossover conditions. Both drugs were significantly effective up to 24 h. The suppressive effect of cetirizine was significantly more rapid and more marked