{"id":105,"date":"2020-05-15T14:09:56","date_gmt":"2020-05-15T14:09:56","guid":{"rendered":"http:\/\/ontsandquants.com\/wp\/?p=105"},"modified":"2020-05-15T14:09:57","modified_gmt":"2020-05-15T14:09:57","slug":"the-reasonable-effectiveness-of-ensembles-in-predictions-for-covid-19","status":"publish","type":"post","link":"http:\/\/ontsandquants.com\/wp\/?p=105","title":{"rendered":"The Reasonable Effectiveness of Ensembles in Predictions for COVID-19"},"content":{"rendered":"\n<p><a href=\"https:\/\/www.npr.org\/sections\/health-shots\/2020\/05\/13\/855038708\/combining-different-models-new-coronavirus-projection-shows-110-000-deaths-by-ju?origin=NOTIFY\">NPR&#8217;s Morning Edition featured a small segment<\/a> on the development of an ensemble model for COVID-19 by a biostatistician at UMASS Amherst, <a href=\"https:\/\/www.umass.edu\/sphhs\/person\/faculty\/nicholas-g-reich\">Nicholas Reich<\/a>.  Basically, combining multiple models intelligently produces a a better model than the individual components.<\/p>\n\n\n\n<p>This finding is helpful if not surprising.  Ensemble techniques have been used in multiple disciplines, especially weather forecasting.  In that application there are two types of uncertainty to be &#8220;integrated out&#8221;:  Uncertainty in the actual initial state and uncertainty from the remaining difference between the model output and the real world.  In some applications with which I&#8217;ve worked in the area of geopolitical forecasting the ensembles feature weighted combinations of alternative models, similar to the ensemble described in the NPR piece.  (According to that piece the COVID-19 ensemble from Reich is an unweighted average of the several model forecasts with accuracy weighting to come in a future version of the ensemble.)  The uncertainty surrounding the initial state doesn&#8217;t really come into play in this domain in the same way that it does with weather forecasting.  In my experience the ensemble isn&#8217;t always uniformly the best model but it&#8217;s never a bad model.  Since we don&#8217;t know <em>a priori<\/em> which of the models will be the best using an ensemble is a nice hedging strategy.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>NPR&#8217;s Morning Edition featured a small segment on the development of an ensemble model for COVID-19 by a biostatistician at UMASS Amherst, Nicholas Reich. Basically, combining multiple models intelligently produces a a better model than the individual components. This finding is helpful if not surprising. Ensemble techniques have been used in multiple disciplines, especially weather &hellip;<\/p>\n<p class=\"read-more\"> <a class=\"\" href=\"http:\/\/ontsandquants.com\/wp\/?p=105\"> <span class=\"screen-reader-text\">The Reasonable Effectiveness of Ensembles in Predictions for COVID-19<\/span>Read More &raquo;<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[],"_links":{"self":[{"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/105"}],"collection":[{"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=105"}],"version-history":[{"count":1,"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/105\/revisions"}],"predecessor-version":[{"id":106,"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=\/wp\/v2\/posts\/105\/revisions\/106"}],"wp:attachment":[{"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=105"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=105"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/ontsandquants.com\/wp\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=105"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}