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	<title>Comments on: Intrade&#8217;s Conditional Prediction Markets</title>
	<atom:link href="http://www.overcomingbias.com/2008/07/intrades-condit.html/feed" rel="self" type="application/rss+xml" />
	<link>http://www.overcomingbias.com/2008/07/intrades-condit.html</link>
	<description>Overcoming Bias is economist Robin Hanson’s blog, on honesty, signaling, disagreement, forecasting, and the far future.</description>
	<lastBuildDate>Mon, 15 Mar 2010 17:03:10 -0400</lastBuildDate>
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		<title>By: Midas Oracle .ORG</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399313</link>
		<dc:creator>Midas Oracle .ORG</dc:creator>
		<pubDate>Tue, 05 Aug 2008 09:41:30 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399313</guid>
		<description>&lt;strong&gt;Subsidizing real-money prediction markets and real-money conditional prediction markets = BULLSHIT IDEA&lt;/strong&gt;

Should Google subsidize the Lunar X Prize contract on InTrade?
John Salvatier,
Our good friend Bo Cowgill might have already re-created those prediction markets on Googles internal prediction exchange at a marginal cost of zero US dollar. No nee...
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		<content:encoded><![CDATA[<p><strong>Subsidizing real-money prediction markets and real-money conditional prediction markets = BULLSHIT IDEA</strong></p>
<p>Should Google subsidize the Lunar X Prize contract on InTrade?<br />
John Salvatier,<br />
Our good friend Bo Cowgill might have already re-created those prediction markets on Googles internal prediction exchange at a marginal cost of zero US dollar. No nee&#8230;</p>
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		<title>By: Silas</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399312</link>
		<dc:creator>Silas</dc:creator>
		<pubDate>Thu, 31 Jul 2008 17:25:33 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399312</guid>
		<description>&lt;a href=&quot;http://silasx.blogspot.com/2008/07/i-just-dont-get-no-respect-about.html&quot; rel=&quot;nofollow&quot;&gt;Blogged and flogged.&lt;/a&gt;

I&#039;ll miss my posting privileges here.  I really will :-(
</description>
		<content:encoded><![CDATA[<p><a href="http://silasx.blogspot.com/2008/07/i-just-dont-get-no-respect-about.html" rel="nofollow">Blogged and flogged.</a></p>
<p>I&#8217;ll miss my posting privileges here.  I really will <img src='http://www.overcomingbias.com/wp-includes/images/smilies/icon_sad.gif' alt=':-(' class='wp-smiley' /> </p>
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		<title>By: Doug S.</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399311</link>
		<dc:creator>Doug S.</dc:creator>
		<pubDate>Wed, 30 Jul 2008 23:41:26 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399311</guid>
		<description>Now, if only Intrade worked in the United States without requiring a bank transfer...
</description>
		<content:encoded><![CDATA[<p>Now, if only Intrade worked in the United States without requiring a bank transfer&#8230;</p>
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		<title>By: Allan Crossman</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399310</link>
		<dc:creator>Allan Crossman</dc:creator>
		<pubDate>Wed, 30 Jul 2008 22:03:04 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399310</guid>
		<description>&lt;i&gt;Why not Democrat and Republican? Those are the two major parties. What about third parties?&lt;/i&gt;

I suspect the intention was to make the probabilities (&quot;Dem presidency&quot; and &quot;non-Dem presidency&quot;) add up to be exactly the same as the probability of any kind of presidency.

&lt;i&gt;&quot;Democratic&quot; is the system of Democracy. Democrat is a political party in America. Although I&#039;m sure the DNC loves how people conflate the two.&lt;/i&gt;

I don&#039;t think it&#039;s a conflation; it&#039;s simply a word with more than one meaning. The word Republican is the same: it also has a meaning distinct from the name of a party.

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		<content:encoded><![CDATA[<p><i>Why not Democrat and Republican? Those are the two major parties. What about third parties?</i></p>
<p>I suspect the intention was to make the probabilities (&#8221;Dem presidency&#8221; and &#8220;non-Dem presidency&#8221;) add up to be exactly the same as the probability of any kind of presidency.</p>
<p><i>&#8220;Democratic&#8221; is the system of Democracy. Democrat is a political party in America. Although I&#8217;m sure the DNC loves how people conflate the two.</i></p>
<p>I don&#8217;t think it&#8217;s a conflation; it&#8217;s simply a word with more than one meaning. The word Republican is the same: it also has a meaning distinct from the name of a party.</p>
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		<title>By: anonymous</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399309</link>
		<dc:creator>anonymous</dc:creator>
		<pubDate>Wed, 30 Jul 2008 19:42:09 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399309</guid>
		<description>Biases?

(1) Column headings:
&quot;Dem price	non-Dem price	Dem norm	non-Dem norm&quot;

Why not Democrat and Republican? Those are the two major parties. What about third
parties?

(2) &quot;non-Democratic administration&quot;

&quot;Democratic&quot; is the system of Democracy. Democrat is a political party in America. Although I&#039;m sure the DNC loves how people conflate the two.

</description>
		<content:encoded><![CDATA[<p>Biases?</p>
<p>(1) Column headings:<br />
&#8220;Dem price	non-Dem price	Dem norm	non-Dem norm&#8221;</p>
<p>Why not Democrat and Republican? Those are the two major parties. What about third<br />
parties?</p>
<p>(2) &#8220;non-Democratic administration&#8221;</p>
<p>&#8220;Democratic&#8221; is the system of Democracy. Democrat is a political party in America. Although I&#8217;m sure the DNC loves how people conflate the two.</p>
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		<title>By: Matt Huang</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399308</link>
		<dc:creator>Matt Huang</dc:creator>
		<pubDate>Wed, 30 Jul 2008 14:02:55 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399308</guid>
		<description>Being argumentative for the sake of argumentation isn&#039;t productive.
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		<content:encoded><![CDATA[<p>Being argumentative for the sake of argumentation isn&#8217;t productive.</p>
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		<title>By: Silas</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399307</link>
		<dc:creator>Silas</dc:creator>
		<pubDate>Wed, 30 Jul 2008 13:57:48 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399307</guid>
		<description>Robin: &lt;i&gt;Silas, as I explained before,&lt;/I&gt;

Where?  Would you mind pointing me to the first comment you made in that discussion, in which you understood what I was proposing, and correctly stated what you meant?  Because that was kind of an issue back then.

&lt;i&gt;we expect that on election day most of the causal direction of the correlation is from the vote to the consequences, while for most days before there are large causal forces in both directions.&lt;/I&gt;

Well, you certainly *hope* so, but then, the market has usually largely incorporated expectations about the winner before election, making the signal really really small, and allowing the random influences to dominate.

Let me take a gander at Peter McCluskey&#039;s shock futures market.  Is it consistent with my theory that bidders will assume that other random forces will determine the election day correlation?

&quot;49.9-50.1&quot;

Yep, that&#039;s betting on a coin flip alright!

&lt;i&gt;Also, we want a market estimate as useful as possible right up until the election, but just before the election the overall correlation price would be dominated by the previous correlation history.&lt;/I&gt;

Yes, so in the unlikely event that the correlation of &quot;probability of democratic win&quot; and &quot;oil futures&quot;  is very far from the unknown noise-filtered, manipulation-filtered election day correlation, this metric will have inaccurate results.

If you really think the election day&#039;s correlation is that much more important, then you can say:

&quot;Silas, that&#039;s a really good idea, but to account for election day&#039;s more relevant information, the metric should treat election day as 30 days of price history for purposes of determining the correlation that resolves the bet.&quot;

Then, you give stronger weight to election day, but still incorporate all the available information and dilute irrelevant influences!

&lt;i&gt;(And do you really imagine I had not considered your obvious variation when I chose my design?)&lt;/i&gt;

I invite anyone to read the thread and decide if Robin&#039;s responses indicate that he had considered the idea before.

P(Robin responds to misunderstandings of my idea &#124; Robin has considered my idea before) = low
P(Robin responds to misunderstandings of my idea &#124; Robin has not considered my idea before) = high
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		<content:encoded><![CDATA[<p>Robin: <i>Silas, as I explained before,</i></p>
<p>Where?  Would you mind pointing me to the first comment you made in that discussion, in which you understood what I was proposing, and correctly stated what you meant?  Because that was kind of an issue back then.</p>
<p><i>we expect that on election day most of the causal direction of the correlation is from the vote to the consequences, while for most days before there are large causal forces in both directions.</i></p>
<p>Well, you certainly *hope* so, but then, the market has usually largely incorporated expectations about the winner before election, making the signal really really small, and allowing the random influences to dominate.</p>
<p>Let me take a gander at Peter McCluskey&#8217;s shock futures market.  Is it consistent with my theory that bidders will assume that other random forces will determine the election day correlation?</p>
<p>&#8220;49.9-50.1&#8243;</p>
<p>Yep, that&#8217;s betting on a coin flip alright!</p>
<p><i>Also, we want a market estimate as useful as possible right up until the election, but just before the election the overall correlation price would be dominated by the previous correlation history.</i></p>
<p>Yes, so in the unlikely event that the correlation of &#8220;probability of democratic win&#8221; and &#8220;oil futures&#8221;  is very far from the unknown noise-filtered, manipulation-filtered election day correlation, this metric will have inaccurate results.</p>
<p>If you really think the election day&#8217;s correlation is that much more important, then you can say:</p>
<p>&#8220;Silas, that&#8217;s a really good idea, but to account for election day&#8217;s more relevant information, the metric should treat election day as 30 days of price history for purposes of determining the correlation that resolves the bet.&#8221;</p>
<p>Then, you give stronger weight to election day, but still incorporate all the available information and dilute irrelevant influences!</p>
<p><i>(And do you really imagine I had not considered your obvious variation when I chose my design?)</i></p>
<p>I invite anyone to read the thread and decide if Robin&#8217;s responses indicate that he had considered the idea before.</p>
<p>P(Robin responds to misunderstandings of my idea | Robin has considered my idea before) = low<br />
P(Robin responds to misunderstandings of my idea | Robin has not considered my idea before) = high</p>
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		<title>By: Michael Sullivan</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399306</link>
		<dc:creator>Michael Sullivan</dc:creator>
		<pubDate>Wed, 30 Jul 2008 13:51:24 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399306</guid>
		<description>I doubt Peter makes a profit on this batch.  That would require a lot of trading with that small a spread.

But in principle you are right.  There&#039;s got to be some sweet spot of volume and good guesstimation of the initial line where this is profitable even with the fairly small bid/ask.

If a somewhat larger spread would still invite interest in the market, it should be fairly easy to make it profitable as long as transaction costs to the market maker are low (much smaller than the spread).
</description>
		<content:encoded><![CDATA[<p>I doubt Peter makes a profit on this batch.  That would require a lot of trading with that small a spread.</p>
<p>But in principle you are right.  There&#8217;s got to be some sweet spot of volume and good guesstimation of the initial line where this is profitable even with the fairly small bid/ask.</p>
<p>If a somewhat larger spread would still invite interest in the market, it should be fairly easy to make it profitable as long as transaction costs to the market maker are low (much smaller than the spread).</p>
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		<title>By: Ben</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399305</link>
		<dc:creator>Ben</dc:creator>
		<pubDate>Wed, 30 Jul 2008 12:35:03 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399305</guid>
		<description>Without knowing anything about the trading algorithm Peter is using, I suspect that subsidize is probably the wrong word for what he&#039;s doing.  Market-making is a very common trading strategy that can be highly profitable if done correctly, even without knowing much about the actual value of what you&#039;re trading.  I&#039;d assume that the algorithm adjusts the bid and ask prices whenever a trade is made, meaning that if the initial market is wrong, the algorithm will correct it.  If there&#039;s enough trading volume, Peter will make enough from the bid/ask spread of 2.5 to cover any losses from the initial market being incorrect.

Props to Peter for taking on the risk in order to get the market going, and more props if he ends up making a profit.  Anyone interested in setting up a prediction market based on whether Peter McCluskey comes out ahead?
</description>
		<content:encoded><![CDATA[<p>Without knowing anything about the trading algorithm Peter is using, I suspect that subsidize is probably the wrong word for what he&#8217;s doing.  Market-making is a very common trading strategy that can be highly profitable if done correctly, even without knowing much about the actual value of what you&#8217;re trading.  I&#8217;d assume that the algorithm adjusts the bid and ask prices whenever a trade is made, meaning that if the initial market is wrong, the algorithm will correct it.  If there&#8217;s enough trading volume, Peter will make enough from the bid/ask spread of 2.5 to cover any losses from the initial market being incorrect.</p>
<p>Props to Peter for taking on the risk in order to get the market going, and more props if he ends up making a profit.  Anyone interested in setting up a prediction market based on whether Peter McCluskey comes out ahead?</p>
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		<title>By: Robin Hanson</title>
		<link>http://www.overcomingbias.com/2008/07/intrades-condit.html#comment-399304</link>
		<dc:creator>Robin Hanson</dc:creator>
		<pubDate>Wed, 30 Jul 2008 12:24:19 +0000</pubDate>
		<guid isPermaLink="false">http://prod.ob.trike.com.au/2008/07/intrades-conditional-prediction-markets.html#comment-399304</guid>
		<description>Silas, as I explained before, we expect that on election day most of  the causal direction of the correlation is from the vote to the consequences, while for most days before there are large causal forces in both directions.  Also, we want a market estimate as useful as possible right up until the election, but just before the election the overall correlation price would be dominated by the previous correlation history.  (And do you really imagine I had not considered your obvious variation when I chose my design?)
</description>
		<content:encoded><![CDATA[<p>Silas, as I explained before, we expect that on election day most of  the causal direction of the correlation is from the vote to the consequences, while for most days before there are large causal forces in both directions.  Also, we want a market estimate as useful as possible right up until the election, but just before the election the overall correlation price would be dominated by the previous correlation history.  (And do you really imagine I had not considered your obvious variation when I chose my design?)</p>
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