This is an old study. Two years ago, we (Jockers et al., 2008) published on this subject, and we reviewed the previous work, including that of Holmes.
Here's a reference for our 2008 study:
Jockers, M. L., D. M. Witten, and C. S. Criddle, 2008. Reassessing authorship of the Book of Mormon using delta and nearest shrunken centroid classification. Literary and Linguistic Computing 23(4): 465-491.
A pre-publication version is available for download here:
http://www.stanford.edu/~mjockers/pubs/LLCPreprintReassess.pdfHere is the Abstract of the 2008 publication:
"Mormon prophet Joseph Smith (1805-1844) claimed that more than two-dozen ancient individuals (Nephi, Mormon, Alma, etc.) living from around 2200 BC to 421 AD authored the Book of Mormon (1830), and that he translated their inscriptions into English. Later researchers who analyzed selections from the Book of Mormon concluded that differences between selections supported Smith's claim of multiple authorship and ancient origins. We offer a new approach that employs two classification techniques: "delta" commonly used to determine probable authorship and "nearest shrunken centroid" (NSC), a more generally applicable classifier. We use both methods to determine, on a chapter- by-chapter basis, the probability that each of seven potential authors wrote or contributed to the Book of Mormon. Five of the seven have known or alleged connections to the Book of Mormon, two do not, and were added as controls based on their thematic, linguistic, and historical similarity to the Book of Mormon. Our results indicate that likely nineteenth century contributors were Solomon Spalding, a writer of historical fantasies; Sidney Rigdon, an eloquent but perhaps unstable preacher; and Oliver Cowdery, a schoolteacher with editing experience. Our findings support the hypothesis that Rigdon was the main architect of the Book of Mormon and are consistent with historical evidence suggesting that he fabricated the book by adding theology to the unpublished writings of Spalding (then deceased)."
Below are our comments on the Holmes' study:
"More compelling than the work of Hilton and Larsen is the work of statistician David Holmes (1985, Holmes, 1991a, Holmes, 1991b, Holmes, 1992). In separate papers from 1991 and 1992, Holmes investigated Book of Mormon authorship using a multivariate measurement of vocabulary richness. Holmes
compared the Book of Mormon to thirteen writing samples from Joseph Smith, Joanna Southcott, and the King James Bible.17 He measured the richness of noun usage in the various works: a technique that Holmes claims enables him to discriminate between the "personal" and the "prophetic" writings of Joseph Smith as well as between the personal writings of Smith and those of Joanna Southcott. Using this technique, Holmes further discriminates between the prophetic voice of Smith and that of Southcott. Holmes's derives the "signal" for Smith's prophetic voice from Smith's revelations as they are recorded in Doctrine and Covenants; the personal voice he derives from the letters and diary entries collected in Dean Jessee's The Personal Writings of Joseph Smith.
Detecting differences between Smith's prophetic and personal voice was a key discovery for Holmes. His technique appeared to prove effective in discriminating between authors and between authorial voices in different contexts. From this, Holmes argued that his multivariate measurements of vocabulary richness offered no evidence to support the argument that the Book of Mormon is a work of multiple authors. This conclusion stood in direct contradiction to the previous analyses by Larsen and Hilton. However, two problems are apparent in Holmes's work: First, his reliance upon the letters and diary entries collected by Dean C. Jessee in Personal Writings of Joseph Smith (Smith and Jessee, 2002) as a reliable source for Smith's personal voice and second his reliance upon the Doctrine and Covenants as a reliable source for Smith's prophetic voice.
Though Holmes was careful to select "only those letters written by Smith himself [in Smith's hand], or preserved in the handwriting of clerks who state specifically that Smith is dictating" (Holmes, 1991b) even this subset of Dean Jessee's collection is problematic. In the opening sentence of his introduction to whether or not a person writes his own journals, letters, and speeches or delegates others to write for him" (Jessee, 2002). His point here is that even if written by others, the material reflects the mind of the Smith if not the actual words as written. For authorship attribution analysis, however, we are less concerned with whether a document captures the "spirit" of an attributed author and more specifically interested in whether the document is written by and in the
natural style of the attributed author. With Smith, however, we cannot reasonably conclude this point, that the documents attributed to him are indeed reflections of his individual literary style. On the contrary, in studying Smith and
reading Jessee's collection of documents, one becomes immediately and acutely aware of how little we can, even blithely, attribute to Smith and Smith alone.
Jessee notes the problems associated with claiming that Smith was the author of the words attributed to him: "His philosophy" writes Jessee, "was that 'a prophet cannot be his own scribe.'"Indeed, even Jessee avoids use of the word "author" preferring instead "writings attributed to him [Smith]." Jessee points out that while Smith "produced a sizable collection of papers, the question remains as to how clearly they reflect his own thoughts and personality [because] we inherit the limitations that produced them . . . the wide use of clerks taking dictation or even being assigned to write for him, and the editorial reworking of reports of what he did and said" (Smith and Jessee, 2002). Jessee notes further
that the "practice . . . of inserting eyewitness writings that have been changed from indirect to direct discourse . . . gives the impression that Joseph wrote them," when in fact he did not. Referring to one particular case, Jessee writes hat the impressions of Joseph Smith given . . . probably reflect the personality of the editor more than they do Joseph's." Even for the twenty-three letters in Smith's hand, which Jessee republishes in facsimile form, we cannot easily assume that Smith is the sole author. Many of the letters in Jessee's collection show the handwriting of Smith along side and intermingled with the handwriting of other authors, including Rigdon and Cowdery. Even when writing something as personal as a journal entry or letter, we see consistent evidence of collaboration and co-authorship. Unfortunately, such writing cannot be used as a reliable sample of known authorship.
Second, and equally problematic, is Holmes's use of the Doctrine and Covenants as a reliable example of Smith's prophetic voice. This text of revelations is ascribed to Smith, but as is the case with many of his letters and diary entries, he did not write it unaided. Rather, he is reported to have dictated the revelations to one of his scribes. From 1829 to 1838, two of Smith’s main scribes were none other than Sidney Rigdon and Oliver Cowdery, who according to the Spalding-Rigdon theory, participated in writing the Book of Mormon. In fact, the Church of Jesus Christ of Latter Day Saints (the Mormon Church) acknowledges that many sections of the Doctrine and Covenants were revealed jointly to Smith and Rigdon or to Smith and Cowdery.20 The voice signals of one of these men or a mix of their signals could be the "prophetic voice" Holmes ascribes to Smith. That Holmes would find similarities between the "prophetic" voice of the Doctrine and Covenants and the Book of Mormon, therefore, is at best evidence of common authorship for the two texts but in no way demonstrates that Smith's "voice" (divinely inspired or otherwise) is anywhere to be found."
Since the 2008 study, Matt Jockers has done some additional work to identify documents that were likely written by Smith.