Not so much a crucial factor in our current world as it was in the olden days, effectiveness measures the ability of a certain something to usurp the place of many other things. For example, a nuclear bomb can replace a standing army (although these two of course have differing situations when they can be used) and also costs far less than a standing army. Another example would be to have Wikipedia replacing Britannica, Encarta, Columbia, World Book, etc... These two are fundamentally different examples of effectiveness. The former stresses power; the latter, globalization: the use of one copy of something for more instances of uses through a larger audience.