{"id":265,"date":"2012-05-03T09:56:04","date_gmt":"2012-05-03T08:56:04","guid":{"rendered":"http:\/\/www.economic-truth.co.uk\/?p=265"},"modified":"2019-06-19T13:16:05","modified_gmt":"2019-06-19T12:16:05","slug":"meeting-in-the-middle-the-clustering-effect","status":"publish","type":"post","link":"http:\/\/www.economic-truth.co.uk\/?p=265","title":{"rendered":"Meeting in the middle: the clustering effect"},"content":{"rendered":"<p>Today sees local elections across the UK, with the highest profile battle being fought over the mayorship of London.&nbsp; While there are two high-profile candidates in Boris Johnson and Ken Livingstone, there are a number of other candidates who represent a whole range of political views from the far right to the far left.<\/p>\n<p>There is a significant third candidate in the middle, Brian Paddick.&nbsp; While he is unlikely to get elected, he has a significant impact on the policies of the two front-runners.&nbsp; There are many differences in policies between the Conservatives and Labour, and this difference is driven by the existence of the third option.&nbsp; <!--more--><\/p>\n<p>This can be compared to the situation with elections in the US.&nbsp; In many cases, policies between the two main parties are almost identical, and this is caused by the lack of a viable alternative to these candidates.&nbsp; This type of convergence derives from the need for political parties to appeal to voters.<\/p>\n<p>Consider a simplified political landscape, with a single spectrum of policies.&nbsp; There are two potential candidates, 1 and 2, and four voters. These four voters are spread across the spectrum as shown below.<\/p>\n<p><a href=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering1.png\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"268\" data-permalink=\"http:\/\/www.economic-truth.co.uk\/?attachment_id=268\" data-orig-file=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering1.png\" data-orig-size=\"644,60\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"Clustering before movement\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering1.png\" class=\"aligncenter size-full wp-image-268\" title=\"Clustering before movement\" src=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering1.png\" alt=\"\" width=\"644\" height=\"60\" srcset=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering1.png 644w, http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering1-300x27.png 300w\" sizes=\"auto, (max-width: 644px) 100vw, 644px\" \/><\/a><\/p>\n<p>As it stands, it is clear that a will vote for 1, and d will vote for 2.&nbsp; This is not to say that these voters completely agree with the policies of their chosen candidate &#8211; indeed, we can see that a believes that 1 is a bit too &#8220;right&#8221; for them, while d considers 2 too &#8220;left&#8221;.&nbsp; However, these candidates are the closest to the ideal.<\/p>\n<p>What about the remaining two candidates?&nbsp; b is likely to vote for 1, since although 1 is a little too &#8220;left&#8221; it is the nearest to the ideal.&nbsp; c is midway between the two candidates and so could be convinced either way.&nbsp; In any case, 2 will not win this election; the best they can hope for is a tie.<\/p>\n<p>It is easy to conclude that all voters to the left of 1 will vote for 1, and all voters to the right of 2 will vote for 2.&nbsp; The election will be decided by the treatment of voters in the middle of the two candidates.&nbsp; By moving along the political spectrum, 2 will be able to capture some of these middle voters, as shown below.<\/p>\n<p><a href=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering2.png\"><img loading=\"lazy\" decoding=\"async\" data-attachment-id=\"272\" data-permalink=\"http:\/\/www.economic-truth.co.uk\/?attachment_id=272\" data-orig-file=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering2.png\" data-orig-size=\"644,60\" data-comments-opened=\"1\" data-image-meta=\"{&quot;aperture&quot;:&quot;0&quot;,&quot;credit&quot;:&quot;&quot;,&quot;camera&quot;:&quot;&quot;,&quot;caption&quot;:&quot;&quot;,&quot;created_timestamp&quot;:&quot;0&quot;,&quot;copyright&quot;:&quot;&quot;,&quot;focal_length&quot;:&quot;0&quot;,&quot;iso&quot;:&quot;0&quot;,&quot;shutter_speed&quot;:&quot;0&quot;,&quot;title&quot;:&quot;&quot;}\" data-image-title=\"Clustering after movement\" data-image-description=\"\" data-image-caption=\"\" data-large-file=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering2.png\" class=\"aligncenter size-full wp-image-272\" title=\"Clustering after movement\" src=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering2.png\" alt=\"\" width=\"644\" height=\"60\" srcset=\"http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering2.png 644w, http:\/\/www.economic-truth.co.uk\/wp-content\/uploads\/2012\/05\/Clustering2-300x27.png 300w\" sizes=\"auto, (max-width: 644px) 100vw, 644px\" \/><\/a><\/p>\n<p>d will still vote for 2, since they represent the best option, even if they are further away from d&#8217;s ideals.&nbsp; c will now definitely vote for 2, since they are closer to 2 than they are to 1.&nbsp; By moving closer to 1&#8217;s position, 2 has won the election.&nbsp; This analysis can be iterated; 1 may move closer to 2 in order to guarantee b&#8217;s vote and force a tie.<\/p>\n<p>In general cases, there are more than four voters and there is a continuum of preferences; due to this, 1 and 2 will move closer and closer to each other until there is little difference between the two. 1 and 2 will end up both positioned in the middle of the spectrum, with equal numbers of voters on each side.<\/p>\n<p>However, entering a third candidate onto this spectrum disrupts the convergence.&nbsp; A third candidate could position themselves to capture both c and d, and 2 would instead move back along the spectrum to recapture lost voters.&nbsp; There is in fact no steady state equilibrium to this situation; any move by any player immediately changes the best response by others.&nbsp; In the UK it can be seen that political parties are constantly moving along the spectrum, with (for example) Tony Blair&#8217;s &#8220;New Labour&#8221; being a more right-wing relaunch of the Labour party.<\/p>\n<p>The situation is made more complex by the fact that there is more than one spectrum to be considered: voters consider how a party will deal with policing, with healthcare, with liberties, with the economy.&nbsp; Rather than examining candidates on a single line, voters will instead carry out some sort of multidimensional <a title=\"Nearest neighbour analysis\" href=\"http:\/\/en.wikipedia.org\/wiki\/K-nearest_neighbor_algorithm\" target=\"_blank\" rel=\"noopener noreferrer\">nearest neighbour analysis<\/a>.&nbsp; As long as there are at least two more candidates than there are dimensions, voters will be left with a choice of policies, rather than being dictated by political parties meeting in the middle.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Today sees local elections across the UK, with the highest profile battle being fought over the mayorship of London.&nbsp; While there are two high-profile candidates in Boris Johnson and Ken Livingstone, there are a number of other candidates who represent a whole range of political views from the far right to the far left. There &hellip; <\/p>\n<p class=\"link-more\"><a href=\"http:\/\/www.economic-truth.co.uk\/?p=265\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;Meeting in the middle: the clustering effect&#8221;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[7],"tags":[22,21,23],"class_list":["post-265","post","type-post","status-publish","format-standard","hentry","category-commentary","tag-game-theory","tag-politics","tag-voting"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p28ZxV-4h","_links":{"self":[{"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/265","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=265"}],"version-history":[{"count":13,"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/265\/revisions"}],"predecessor-version":[{"id":715,"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=\/wp\/v2\/posts\/265\/revisions\/715"}],"wp:attachment":[{"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=265"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=265"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.economic-truth.co.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=265"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}