Well, lloyd finally got me the data over the weekend, but I couldn't analyze it until tonight. It is only data from 2012 and 2013, but that should be enough for an initial analysis.
I'm not sure what he did with his Excel template, but I (like the earlier commenters) couldn't find any real correlations related to vote totals.
However, I did find some interesting things when looking at the sales data (instead of vote data) that would support some of his comments.
In thinking about the data, it seemed to make the most sense to look at first-day sales data, rather than overall sales data (to cut out having to deal with the vagaries of the reckoning, prices, etc.), which was supported by the (somewhat obvious) strong liner correlation between first-day and overall sales data.
Looking at the time-series sales data, there is significantly less erosion of sales than there is with derby votes in 2012-2013. Even so, there is a downward trend in sales during this period.
So first, I did a direct comparison of the different sales types (where "Derby 1" = first place in the derby; and Old/New is the old vs. new determination of derby winners) across the entire year.
From this, we can see that 1st Place in the Derby, both pre- and post- rules change (and 1st Place in the Double-Take) are not significantly different from one another, and result in significantly higher sales than all of shirt sale types.
We can also see that the only Level containing the Guest Editor's Choice ("Derby 3: New") - Level D - results in significantly lower sales than other Levels of sales.
So, there is evidence that the GEC is significantly costing Woot shirt sales.
Now, we know that overall sales decreased over the time period we're looking at, so I ran the Oneway analysis both pre- and post- rule change.
Prior to the rule change, sales of the Derby winner were significantly higher than all other types of shirt sales. All other types of shirt sales were not significantly different from one another. (I'm ignoring the double-take data, which has a high standard deviation because of the small samples size.)
After the rule change, the top level remained similar to pre-rule change (as we would expect), but another level emerged, in which the GEC was only present in the lowest Level.
So, curious to try and compare the Old Derby 2nd and 3rd place to the New Derby EC and GEC, while trying to account for the loss in sales over the year, I decided to look at the percent "loss" in sales between the First place entry, and the other two derby winners.
Interestingly, the 3rd place Derby winner in the old system had a significantly lower drop in sales (relative to the derby winner) than the 2nd place Derby winner in the old system. This is reversed in the new system.
And finally, I used the overall sales numbers (not just the first day sales) to compare the different types of shirt sales, just to see if it made the picture any clearer.
So - with all of the evidence in Lloyd's sample - it appears that sales for the 2nd place winner (the EC) in the new rules are less than in the old system, but not significantly. However, the evidence does seem to show that the Guest Editor Choice is, indeed, costing Woot shirt sales.
Additionally, one of the stated aims of the new voting/selection system was to help newer artists print more often.
One way to look at this (since my data set is incomplete) is to see how many first-time artist prints (by percentage) pre- and post- rule changes.
In 2012-2013, 31 of 194 daily entries (16%) were first-time artists. Prior to the rule changes, 11 of 84 derby winners (13%) were first-time artists. After the rule changes, 5 of 66 (8%) derby winners were first-time artists. (I can't really do a full analysis of the "spreading" of wins without full data, so I can't go much farther here).
As to lloyd's other comment about 2nd and 3rd place finishers (in the votes) in the new system not receiving an HM, this has happened some (which was why he initially asked me about my feelings on it, since he knew that I'd had a design in that category). As it turns out, I guess I'm the unluckiest artist in this regard.
In the new system, 44% of the 2nd and 3rd place finishers (in the voting) still printed as an EC or GEC. 41% of the 2nd and 3rd place finishers received an Honorable Mention. 15% received nothing at all (no print, no HM).
(Personally, I had four 2nd or 3rd place vote finishes during the time period, one of which printed, and the other three were not HM's.)
I can't really say how many of the 2nd/3rd place finisher HM's will print, since not all of them have gone through the double-take yet.
So - while there is some anecdotal evidence for lloyd's comment/suggestion, I'd say there's not enough data to conclude some sort of favoritism (or, in my case, anti-favoritism).