1. A computerized method for detecting plagiarism in a set of electronic constructed responses, the method performed by a computer comprising a processor executing a set of computer-readable instructions stored in a non-transitory computer readable memory, the method comprising the steps of: receiving, by the computer, the constructed responses over a communications network from a database; pre-processing, by the computer, the constructed responses in parallel to automated or manual scoring of the constructed responses; identifying, by the computer, at least two pairs of the constructed responses; calculating, by the computer, for each of the at least two pairs, a respective similarity value based on a minimum number of operations needed to transform one of the constructed responses of the pair into the other constructed response of the pair, wherein the operations include appending and deleting, but wherein the operation of appending to either end of a shorter constructed response of the pair and the operation of deleting from either end of a longer of the constructed response of the pair do not affect the similarity value; determining, by the computer, zero or more instances of plagiarism by comparing the similarity values with a similarity threshold indicative of plagiarism; and, performing, by the computer, in response to the determining of zero or more instances of plagiarism, at least one of: voiding a score in a score database over the network and terminating the process so that scores for the constructed responses are not voided.