Abstract: Methods, apparatus, systems, and articles of manufacture to perform computer-based monitoring of audiences of network-based media using information theory to estimate intermediate level unions are disclosed. An example apparatus to determine a deduplicated, census-based audience metric of media includes panel union calculator circuitry to calculate a threshold statistic corresponding to an intermediate union of a panel hierarchy, and census union calculator circuitry to calculate a deduplicated audience value corresponding to the intermediate union of the census hierarchy based on the threshold statistic.

Abstract: A stern drive unit for incorporation in the drive leg of a stern drive or outboard drive of a watercraft comprises an intermediate drive shaft (8) mounted for axial translatory movement within an outer housing (1) and splined at its upper end for driven engagement with an input drive shaft (23) of the stern or output drive. The intermediate shaft (8) carries upper and lower gears (9, 10) that are rotatable relatively to the intermediate shaft (8) but can be coupled thereto by means of friction clutches recessed within the respective gears. The intermediate shaft (8) can be driven axially relatively to the housing (1) in each of two directions by means of a hydraulic piston and cylinder arrangement (26-33). A collar (15) fixed with respect to the intermediate drive shaft (8) is arranged to actuate the respective friction clutches in each direction of translatory motion whereby the intermediate shaft (8) can be directly coupled either to the gear (9) or the gear (10).