Upon looking over my notes for this blog entry I find that my original idea was interesting, but not doable. I had been thinking about the fact that the closest any two chronologies came to agreement was 40%. In other words, only 40% of the time did two of the major chronologists agree on the timeline of any of the stories. (To be fair, I do not know which two those are, but I will look into it more at a later time.)
Along that same line of thinking I began to wonder about the length of time between dates that they had settled upon for the stories. E. B. Zeisler's date for The Hound of the Baskervilles (HOUN) doesn't match William S. Baring-Gould's: Gavin Brend's dating of 'The Adventure of the Copper Beeches' (COPP) doesn't agree with June Thomson's, etc. So, I thought it might be interesting to look at this info and see where some of them stood.
I would like to say up front that of all of the chronologies I have only one has an actual date for each story. Brad Keefauver managed to place an actual day of the week, month, and year to each of the 60 stories. (I suspect, however, that at times he settled upon a date because it didn't conflict with anything, and it fit with the evidence. I have done this numerous times. It goes something like this: "There is nothing in this tale to tell us the precise date of it, but as we know it had to have happened on a Friday sometime around the middle of May of 1889, I'll just go with Friday, May 17th.*)
*Not part of an actual dating of mine. Totally generic.
I began looking at my spreadsheets and found that there are some stories which almost everyone agrees on with approximate dating. Howard W. Bell, T. S. Blakeney, Brend, and John Hall all say that 'The Adventure of the Dying Detective' (DYIN) occurred in November. They don't always agree on the year, but none could find enough data to say what day in November. Henry Folsom, Hall, and Roger Butters all say 'The Adventure of the Five Orange Pips' (FIVE) took place in September of different years, but again can't pin a date down. This would make comparing full chronologies against each other a bit difficult so I thought we might just look at a few examples instead of entire works.
The aforementioned HOUN is a good place to start. The Canon tells us that the story starts in October of 1889. What do the people say? Well...
Earliest: Bell thinks the correct dating is September 28, 1886.
Latest: Zeisler, Dakin, and Folsom all say it was September 25, 1900.
Difference: 13 years, 11 months, 29 days!
'The Adventure of Shoscombe Old Place' (SHOS) is a fine example of this wide spread, as well. All The Canon says is May - no year.
Earliest: Jay Finley Christ says it was May 9, 1883.
Latest: Keefauver and I both agree on May 26, 1903.
Difference: 20 years, 18 days.
And what about 'The Adventure of Wisteria Lodge' (WIST)? The Canon says late March of 1892.
Earliest: Christ says March 21, 1892.
Latest: Zeisler says it was March 24, 1902.
Difference: 20 years, 3 days.
There are other examples like these, but the chronologists didn't have specific dates. 'The Adventure of the Mazarin Stone' (MAZA) has timelines that range from 1894 to early-to-mid 1903. 'The Adventure of the Red Circle' (REDC) has disagreement that stretches from 1883 to Summer 1903. This isn't always the case as most of the dates fall with just a few years of each other for most of the stories, but as you can see not only is it almost tough to get a lot of congruity, sometimes it's impossible.
(I would like to point out that there is a chronology written by Carey Cummings that would have changed a few of the differences, but Mr. Cummings chronology is not complete. He only dated 27 of the 60 and as such his dates cannot be wholly relied upon as accurate.)