{"id":2192,"date":"2019-12-12T15:21:09","date_gmt":"2019-12-12T15:21:09","guid":{"rendered":"https:\/\/marriott-stats.com\/nigels-blog\/?p=2192"},"modified":"2020-01-02T10:47:05","modified_gmt":"2020-01-02T10:47:05","slug":"uk-general-election-2019-1-my-official-forecast","status":"publish","type":"post","link":"https:\/\/marriott-stats.com\/nigels-blog\/uk-general-election-2019-1-my-official-forecast\/","title":{"rendered":"UK General Election 2019 #1 – My Official Forecast"},"content":{"rendered":"

My forecast for the 2019 UK General Election this Thursday is that the Conservatives will win a majority of 72 seats.\u00a0 The margin of error in this forecast is very wide though due to the fact that 5 of of the last 7 general elections have seen a major polling error.\u00a0 If there is a repeat of the GE2017 underestimate of Labour<\/a>, then there will be another hung Parliament.<\/p>\n

<\/p>\n

Breakdown of My GE2019 Forecast by Region<\/strong><\/span><\/h4>\n

I expect the Conservatives to make a net gain of 43 seats which will more or less come from England since their expected gains in Wales will be cancelled by losses in Scotland.<\/p>\n

\"\"<\/p>\n

This would be Labour’s worst ever post-WW2 election beating the nadir of 1983.\u00a0 The so-called “red wall” of the North & Midlands will be decisively breached with seats turning Conservative for the first time ever.\"\"<\/p>\n

The Liberal Democrats are expected to gain 8 seats to end up on 20 seats.\u00a0 However my model has a rather aggressive tactical voting model and it states that 11 of their seats will be\u00a0the result of tactical voting.\u00a0 If this doesn’t materialise, then they could end up losing seats.\u00a0 I explain my tactical voting model later on.<\/p>\n

\"\"My final forecast is a weighted average ( 50%:25%:25 ) of these 3 scenarios regarding polling errors –<\/p>\n

    \n
  1. A 4% underestimate of the Conservative lead over Labour as happened in 2015.<\/li>\n
  2. No error in the Conservative lead over Labour as happened in 2010.<\/li>\n
  3. A 4% overestimate of the Conservative lead over Labour as happened in 2017.<\/li>\n<\/ol>\n

    I came up with this weighting method after reviewing why I got my 2017 General Election forecast wrong<\/a>.<\/p>\n

    If you would like to comment on my forecast and to see a list of seats changing hands, please visit this twitter thread<\/a>.<\/p>\n

     <\/p>\n

    Breakdown of My Forecast by Seat<\/span><\/strong><\/h4>\n

    To see my predictions at the seat level, please download this spreadsheet (1MB) – GE19 Seat Forecast v2.1<\/a><\/strong><\/span><\/h4>\n

    If you see a seat forecast that doesn’t look right to you then please email me<\/a> or comment on this Twitter thread<\/a>.\u00a0 You will see that the spreadsheet also includes the YouGov MRP seat forecasts<\/a> as well as any individual polls of seats that have taken place (26 in all).\u00a0 Like YouGov, I have no intelligence on specific local conditions which might explain why my number could look odd to you.<\/p>\n

    By the way, I have put all notable independents that I am aware of e.g. Dominic Grieve, under the IGC (Independent Group for Change) label rather than under OTH (Other) label.\u00a0 I believe IGC (formerly Change UK) are only running 3 candidates but doing it this way made it easier for my spreadsheet to do the calculations.<\/p>\n

     <\/p>\n

    Which Opinion Polls did I use to make my forecast?<\/strong><\/span><\/h4>\n

    I have been the polls in depth since the summer of this year.\u00a0 Data from 10 pollsters have been recorded and I have taken the average of these to create these two tables.<\/p>\n

    \"\" \"\"<\/p>\n

    For more details on this data, please read my latest Voting Intention Tracker<\/a><\/strong><\/span>.<\/p>\n

     <\/p>\n

    How does my Seat Forecasting Model work?<\/strong><\/span><\/h4>\n

    There are 5 steps to my seat forecast.\u00a0 Each step uses an abbreviation to denote the model I use.<\/p>\n

      \n
    1. POLLS<\/strong><\/span> – Estimate vote shares assuming all parties are standing based on the poll summaries shown in the tables in the previous section.<\/li>\n
    2. NURS<\/strong><\/span> – Estimate vote shares assuming all parties are standing based on the 25 individual seat polls which I have used to develop a Non-Uniform Regional Swing model or NURS.<\/li>\n
    3. PRE<\/strong><\/span> – take an average of the POLLS & NURS estimates<\/li>\n
    4. STD<\/span> <\/strong>– reallocate votes to account for parties standing down in some seats.<\/li>\n
    5. TV<\/span> <\/strong>– reallocate votes further to take into account probable tactical voting.<\/li>\n<\/ol>\n

      I describe these models below.<\/p>\n

      Step 1 – POLLS<\/strong><\/span><\/h4>\n

      I am using a method I first described for the Peterborough and Brecon & Radnor byelections<\/a> earlier this year.\u00a0 From the tables in the previous section summarising the polls, you can see that I have been tracking 4 breakdowns of the electorate.<\/p>\n

        \n
      1. By Region (RGN<\/strong><\/span>)<\/li>\n
      2. By GE2017 Vote (GE17<\/strong><\/span>)<\/li>\n
      3. By EU16 Referendum Vote (BRX<\/strong><\/span>)<\/li>\n
      4. By Socio-Economic Group (SEG<\/span><\/strong>)<\/li>\n<\/ol>\n

        I decided to build models for each breakdown and then take a dynamic weighted average of these models.\u00a0 For reasons I explain below, I actually created two BRX and two SEG models so I ended up with 6 models in all.<\/p>\n

        UPDATE 1500 12th December – due to pressure of time, I have not been able to complete this section.\u00a0 However if you click on the link above, you will get a good flavour of my method which I largely stuck to.<\/em><\/span><\/p>\n

        STEP 2 – NURS<\/strong><\/span><\/h4>\n

        One of the key insights I had from my forecast error for the 2017 General Election is that I had exactly the right model which was also a NURS (Non-Uniform Regional Swing) model<\/a> but I had the wrong input data in the form of the polls.\u00a0 Although it was with the benefit of hindsight, I did have a clue as to the polling error from a chart I had produced before the election.\u00a0 You will find this chart and the clue it contained about halfway down in my review of my GE2017 forecast<\/a>.<\/p>\n

        I am making the assumption that a NURS model will work again.\u00a0 One of the problems I had with the 2017 election was a dearth of polls for individual seats.\u00a0 This time, both Survation and Deltapoll have carried out polls in 26 seats, some more than once.\u00a0 I have developed my NURS model using just these polls but instead of trying to predict the change in the Conservative lead over Labour as I did in 2017, this time I am trying to predict the change in the “Leave Alliance” lead over the “Remain Consortium”.\u00a0 One poll for the Cambridge seat took place well before the election so I ignored that and used the other 25 seats to produce this chart which pretty much explains everything.<\/p>\n

        \"\"<\/p>\n

        As you can see, my model is able to explain 91% of the change in the “Leave” lead over “Remain” using 3 variables.<\/p>\n

          \n
        1. The % voting leave in 2016 based on my own leave share estimates<\/a> not Chris Hanretty’s.<\/li>\n
        2. The % classed as being in the C2DE socio-economic group.<\/li>\n
        3. Whether or not, a Brexit Party candidate is standing.<\/li>\n<\/ol>\n

          The parameters are different for seats in the London region compared to the rest of England & Wales.\u00a0 Unfortunately there were no seat polls for Scotland during the election so I have assumed that the London model will hold in Scotland since both areas voted Remain in 2016.<\/p>\n

          Step 3 – PRE<\/strong><\/span><\/h4>\n

          This is simply the average of the POLLS & NURS vote shares.<\/p>\n

          Step 4 – STD<\/span><\/strong><\/h4>\n

          When parties stand down the votes are simply reallocated to fellow parties within the Leave Alliance and Remain Consortium.\u00a0 The one exception is the Brexit Party where I allocate 2\/3 to the Conservatives and 1\/3 to Labour.\u00a0 This is to account for the possibility that the Brexit Party is attracting Labour Leavers who may not decide to vote Tory if the Brexit party is not standing.<\/p>\n

          Note I do not consider the SNP to be part of the Remain Consortium because of the Scottish Independence angle to politics in Scotland.<\/p>\n

          Step 5 – TV<\/span><\/h4>\n

          I have used an aggressive tactical voting model whereby at least 50% of the votes from the poorest performing parties within the Leave Alliance and Remain Consortium are reallocated to the best performing party after the STD stage.\u00a0 I am not convinced that tactical voting will be that strong but at present this model is reducing the Conservative total by 20 seats.\"\"<\/p>\n

          UPDATE 1500 12th December – I will update this further when I get a chance!<\/span><\/em><\/p>\n

           <\/p>\n

          — More on Election Forecasting —<\/strong><\/span><\/h4>\n

          To see other forecasts I have made, please click on these links.<\/p>\n

            \n
          1. My 2019 UK European Parliament Forecast<\/a><\/li>\n
          2. Review of my 2017 UK General Election Forecast<\/a><\/li>\n
          3. My 2017 UK General Election Forecast<\/a><\/li>\n
          4. Review of my 2017 Copeland & Stoke Central By-Election Forecasts<\/a><\/li>\n
          5. My 2015 UK General Election Forecast<\/a><\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"

            My forecast for the 2019 UK General Election this Thursday is that the Conservatives will win a majority of 72 seats.\u00a0 The margin of error in this forecast is very wide though due to the fact that 5 of of the last 7 general elections have seen a major polling error.\u00a0 If there is a […]<\/p>\n","protected":false},"author":3,"featured_media":2208,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[2,6],"tags":[23,21,25,140,139,16,45],"class_list":{"0":"post-2192","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-elections","8":"category-forecasting","9":"tag-brexit","10":"tag-election-forecasting","11":"tag-forecasting-model","12":"tag-ge2019","13":"tag-general-election-2019","14":"tag-politics","15":"tag-seat-forecast","16":"entry","17":"override"},"_links":{"self":[{"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/posts\/2192","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/comments?post=2192"}],"version-history":[{"count":9,"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/posts\/2192\/revisions"}],"predecessor-version":[{"id":2253,"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/posts\/2192\/revisions\/2253"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/media\/2208"}],"wp:attachment":[{"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/media?parent=2192"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/categories?post=2192"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/marriott-stats.com\/nigels-blog\/wp-json\/wp\/v2\/tags?post=2192"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}