The extent to which a sentence reads naturally.
Ease with which a translation can be understood, i.e. its clarity to the reader. (Halliday in Van Slype's Critical Report) .
This has also been called fluency, intelligibility, and clarity.
Crook & Bishop (in Van Slype's Critical Report): Cloze test (every eighth word).
Crook & Bishop (in Van Slype's Critical Report): 7-point scale.
Halliday (in Van Slype's Critical Report): Clozentropy.
Sinaiko (in Van Slype's Critical Report): Multiple-choice questionnaire + Cloze test (every fifth word) + clarity measurement + time measurement.
Sinaiko (in Van Slype's Critical Report): Rating of sentences read on a 3-point scale.
Carroll (ALPAC report): rating of sentences read on a 9-point scale.
Carroll & Bishop (in Van Slype's Critical Report): rating of sentences on a 7-point scale.
Leavitt (in Van Slype's Critical Report): rating of texts read on a 9-point scale.
Van Slype (in Van Slype's Critical Report): rating of sentences read in their context on a 4-point scale.
Vauquois (in Van Slype's Critical Report): rating of sentences read on a 2-point and 3-point scale.
Pfafflin (in Van Slype's Critical Report): Rating of sentences read on a 3-point scale.
Vanni & Miller (2001, 2002): "Do you get it?" - snap judgement rating of sentences on scale from 0 to 3.
Niessen, Och, Leusch and Ney, 2000 measure syntactic errors with an automated string edit distance metric, which according to them can also be used as a measure of readability. See also Wellformedness (2.2.1.3/186).
Somers' use of cloze test (Somers and Wild, 2000).
READING TIME is another metric that has been used to measure readability. It is defined as the time required to read and understand a text, or to realize its unintelligibility, but not to memorize it (Van Slype). The following metrics based on reading time are from Van Slype's Final Report):
B.H.Dostert: by asking final users to state what percentage of additional time they require to read MT, as compared to an original in their own language.
J.B. Carroll: by measuring the time spent by the evaluator in reading each sentence of the sample.
G. van Slype: by measuring the time spent by the evaluator in reading each text of the sample.
Pfafflin and Orr (both quoted by T.C. Halliday): by measuring the response time to a multiple-choice questionnaire.
H.W. Sinaiko: by measuring the time necessary for the execution of the cloze test.
Readability is intended to be a metric applied at the sentence-level. This is in contrast to the opinion expressed by Battelle: "Like the MT evaluation methods based on the factor of comprehensibility, evaluation methods based on the concept of readability must consider, if not the whole, then at least a sizable segment of the translated material. This requirement is due to the fact that the method, although called readability method, measures the appropriate overall contextual cohesiveness" (Battelle report).
Readability is a quality of the output that can be measured independently of the source language.
Cloze tests can be used either at sentence-level or cross-sentence level.
This quality has been merged with clarity, which was a separate taxon in earlier versions of this taxonomy.