Planning to tweak the votermedia award algorithm

As I've been watching how the contest is working at votermedia.org/ubc, it seems to me we can tweak one of the model's parameters to make it work a little better. This parameter affects the trade-off between two things we'd like to achieve, both of which encourage competition but in different ways:

1. Limit the maximum share each blog can win. Currently with 5 or more competitors, the maximum votable amount is 30%. This ensures that at least 4 blogs can get funding, thus enhancing competition that way.

2. Even though their shares are at or near the 30% cap, we'd still like the top blogs to feel some incentive to keep making an effort. If the top 3 are all up against a hard ceiling at 30%, they may have little or no incentive to keep working at their blogs.



A parameter that affects this is what I call the "interpolation range". We originally created it because voting is multiple-choice. If the choices are 5% apart, then a non-interpolated algorithm would have awards that jump suddenly from one choice to the next -- e.g. stuck at 20% for a while, then suddenly the next day 25%. So instead we interpret each vote as spread evenly across a 5% range, e.g. a vote for 20% is spread from 17.5% to 22.5%. This smoothes out the award response to changing support levels in a reasonable way.

It also has the nice side effect of leaving a little wiggle room for competition around the 30% ceiling. Getting more votes at 30% will gradually push a blog's award up from 28% to 29, 30, 31 and max 32, although it's very hard to reach 32%, since only one-tenth of each vote would count. AMS Confidential is at 32% now mainly because their older votes at 40% (the maximum vote when there were only 4 competitors) haven't fully decayed yet.

Looking at the shares now at votermedia.org/ubc, and the recent share changes that we can see at votermedia.org/ubc/horserace, I think we can manage this trade-off better by changing the interpolation range from 5% to 10%. Reasons:

- A 4-point range isn't much incentive for the top 3 blogs to compete. 10% range would result in about an 8% effective range of likely award shares -- more incentive to compete.
- The fourth blog would still have an easy opportunity to get some funding, but would have to work for it a little more than now -- not necessarily a bad thing.
- 10% range would take out the "air pocket" that AMS Confidential dropped through on November 18 (see votermedia.org/ubc/horserace) -- the drop would start earlier and end later, becoming more gradual, which seems to me more realistic, and less an artifact of the algorithm.

I tested the calculation yesterday. It would have changed yesterday's awards as follows:
- AMS Confidential up 2% from 32% to 34%
- 11' Eleven" up 1% from 30% to 31%
- Tyler's Blog down 3% from 9% to 6%

I wouldn't focus too much on these specific numbers. At other times in future it's likely to play out differently. Again, AMS Confidential's lead is mostly from old 40% votes that are decaying away anyway. I've been happy to see a fourth challenger (Tyler) moving up, and I'm not eager to slow him down. But I think as a general long-term principle of competition, this change would be healthy.

I phoned Tyler and explained all this to him. He said he doesn't have a problem with it. (Thanks Tyler!) I've also briefed the AMS Elections Administrator, Erik MacKinnon (email elections[at]ams.ubc.ca).

Your comments welcomed here or by email to mark[at]votermedia.org. I plan to phase this in tonight unless I hear some compelling objections. Since this is an experimental contest, we've reserved the right to make changes as we go along -- see Terms.