A random experiment which results in some ordering of theMeventsE1,E2, ···,EMmay be such that these events are observable not individually, but in the form of ordered subsets. A discussion is given for the partial order problem of determining information about one or more complete orders of theMevents from partially ordered observations. Relationships are mentioned between the (rank-order) methods of the present paper and those of Rank Correlation and thek-sample problem.