Question: What are wordprints? What do they have to do with the Book of Mormon?
Answer: As John Hilton put the matter, if wordprinting is a valid technique, then this analysis suggests that it is "statistically indefensible" to claim that Joseph, Oliver, or Solomon Spaulding wrote the 30,000 words in the Book of Mormon attributed to Nephi and Alma. The Book of Mormon also contains work written by more than one author. Critics who wish to reject Joseph's account of the Book of Mormon's production must therefore identify multiple authors for the text, and then explain how Joseph acquired it and managed to pass it off as his own.
Neal A Maxwell Institute
Wayne A Larsen and Alvin C Rencher, “Who Wrote the Book of Mormon? An Analysis of Wordprint, Book of Mormon Authorship, (1982): “Our approach is sometimes referred to as the science of stylometry, which can be defined loosely as statistical analysis of style. It is also called computational stylistics. We do not use the word style in the literary sense of subjective impressions characterizing an author's mode of expression. We must deal with countable items which are amenable to statistical analysis. We look then for what is frequent but largely unnoticed, the quick little choices that confront an author in nearly every sentence. Such choices become habits, so the small details flow virtually without conscious effort.”
Detailed Questions and Answers
What is a wordprint?
Wordprinting, or "stylometry" as it is more commonly known, is the science of measuring literary style. The main assumption underlying stylometry is that an author has aspects of literary style that may be unconsciously used, and can be used to identify their work. Stylometrists analyze literature using statistics, math formulas and artificial intelligence to determine the "style" of an author's writing.
Because authors may write on a variety of topics, the vocabulary they use may vary considerably. Researchers often attempt to use "non-contextual words" in their analyses to avoid this problem: patterns in the use of these words (e.g. such as: and, if, the, etc.) will be less influenced by a change in subject matter.
Debate about the value of wordprints persists, though it has been used in some academic settings to identify previously-unknown authors. Readers are cautioned that the results of wordprint analysis of the Book of Mormon are only as reliable as they would be for other written works, and that "the jury is still out" as to whether wordprints can actually do what their advocates hope. The statistical analyses are not generally disputed; the points of contention revolve around the assumptions which undergird the statistics.
The initial Book of Mormon wordprint studies were carried out by Larsen, Rencher, and Layton. They compared twenty-four Book of Mormon authors (each having at least 1,000 words) to each other, and concluded on the basis of three separate statistical tests that these authors were distinct from each other and Oliver Cowdery, Joseph Smith, Jr., and Solomon Spaulding.
These efforts were critiqued in Ernest H. Taves, Trouble Enough: Joseph Smith and the Book of Mormon (Buffalo, N.Y.: Prometheus Books, 1984), 225–60. John Hilton characterized Taves' review as "fundamentally flawed," and noted that his effort "therefore did nothing to add to or detract from their work." 
An LDS author considered some of Larsen, Rencher, and Layton's work in D. James Croft, "Book of Mormon 'Wordprints' Reexamined," Sunstone no. (Issue #6) (March-April 1981), 15–21. off-site Croft pointed out some flaws in their assumptions, and was cautious about whether wordprint evidence should be accepted or rejected as it then stood.
John Hilton and the Berkeley Group
A more sophisticated approach was taken by John Hilton and non-LDS colleagues at Berkeley. The "Berkeley Group's" method relied on non-contextual word patterns, rather than just individual words. This more conservative method was designed from the ground up, and required works of at least 5,000 words.
The Berkeley Group first used a variety of control tests with non-disputed authors (e.g. works by Mark Twain, and translated works from German) in an effort to:
· demonstrate the persistence of wordprints despite an author's effort to write as a different 'character'
· demonstrate that wordprints were not obliterated by translation (e.g. two different authors rendered by the same translator would still have different wordprints).
The Berkeley Group's methods have since passed peer review, and were used to identify previously unknown writings written by Thomas Hobbes.
The Berkeley Group compared Book of Mormon texts written by Nephi and Alma with themselves, with each other, and with work by Joseph, Oliver, and Solomon Spaulding. Each comparison is assessed based upon the number of "rejections" provided by the model. The greater the number of rejections, the greater the chance that the two texts were not written by the same author. Tests with non-disputed texts showed that two texts by the same author never scored more than 6 rejections; thus, one cannot be certain if scores between 1–6 were written by the same or different authors. Scores of 0 rejections makes it statistically likely the two texts were written by the same author.
However, seven or more rejections indicates that the texts were written by a different author with a high degree of probability:
# of Rejections Certainty of being different authors
The results are striking:
Recall that any test over 6 indicates different authorship; 1–6 or less is indeterminate; 0 is same author. Each x represents one test.
Go to this link for charts and endnotes. http://en.fairmormon.org/Book_of_Mormon_wordprint_studies