Calling the results of F-K tests indications of reading grade level is actually misleading. The F-K test only serves to measure average word and sentence length, and possibly also the amount of passive sentences in a document. Nothing more. We could use the F-K test within Microsoft Word on a document written in another language, say, Spanish. We would then click on Tools, then Spelling and grammar. We would, obviously, immediately encounter words which the spell-checker did not recognize. But this is OK for the F-K test since it doesn't test for whether or not a word is contemporary, obsolete, its register, or even what language it is. We tell the spell-checker to Ignore All instances of all the "misspelled" words in the document. When all the words have been processed, we will get the F-K ease of reading and reading level results. If the Spanish words are of reasonable short length, F-K will tell us that the document has a low reading level. But those results are meaningless, since they are on a language not spoken or read by those for whom we are attempting to compute grade level
And what if we were to process a Cheyenne language document with the Spelling and grammar checker. Cheyenne verbs are typically long, some very long, up to 50 or more letters in length. A single verb can have the meaning of an entire sentence in English. If the Cheyenne document has mostly verbs (and some Cheyennes texts do), then the F-K results would be off the chart. Yet the content theoretically might be no different from that of an English text or a Spanish text.
I hope it is now clear that the Flesch-Kincaid test is appropriately used for certain kinds of texts and not for other texts. F-K results are not accurate for Bible versions which do not have contemporary vocabulary or syntax. We need other testing instruments which can determine if a word is obsolete or not, or if some syntactic form is non-standard for English to be used with Bible versions which are not written in good quality literary current English.
Categories: Flesch-Kincaid, Bible versions, reading level