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How to keep on top of federal election trends with CBC's Poll Tracker

07/15/2015 05:00 EDT | Updated 07/14/2016 05:59 EDT
With CBC's Poll Tracker you can follow the changing fortunes of the major federal parties according to the most recent polls and find out how each party's support translates into seats, according to projections by ThreeHundredEight.com's Éric Grenier.

The Poll Tracker brings together several tools in one place to track the trends in recent public opinion polls using Grenier's polling averages and compare the parties' projected seat totals by region and against the results of the last election. Here's a look at how to use the interactive tool.

- Interactive: Try CBC's Poll Tracker

The poll averages represent an aggregation of all publicly released polls, weighted by age, sample size, and the track record of the polling firm. That has the benefit of smoothing out the normal effects of sampling error and methodological differences that can cause a party's support to wobble back and forth, often within the margin of error, from one poll to the next. A full explanation of how the polls are aggregated can be found here.

The poll averages chart shows the latest numbers and the shift in voting intentions since the previous projection update. To use the chart, simply tap or click on the arrows in the right-hand corner, or directly on the line graph, to see how the aggregate has changed over time. You can also take a closer look at what the polls are showing at the regional level. If you want to focus on just one or two parties, you can click or tap on the signs below the line chart to exclude other parties from the graph.

The seat projections show the best estimate of how current polling levels would translate into seats, an important consideration as the results of Canada's first-past-the-post system do not always line up with national or regional vote shares. The seat projections are calculated with a proportional swing system, shifting the results from 2011 in each riding according to how the polls have shifted in each region of the country. A full explanation of how the seat projection model works can be found here.

The seat projections chart shows the latest estimate, but you can also toggle between the minimum, low, high, and maximum projections to see what each party's likely range of seats is by clicking or tapping on the options below the chart, or directly on each party.

The regional breakdown for the seat projectionsshows how the national projections are distributed by party and region according to the latest numbers as well as the results of the 2011 election. To see how each party's projected seat haul breaks down by region, simply tap or move your mouse over that party on the left-hand side of the graphic. To see how each region's projected outcome breaks down by party, simply tap or move your mouse over that region on the right-hand side.

The list of polls is a complete listing of all the national polls that have been conducted in 2015 and included in the aggregation. You can sort by pollster, date, sample size, party support or methodology by clicking or tapping on the column header. You can also see each pollster's full report by clicking or tapping on the link in the left-hand column.

The Poll Tracker will be updated throughout the pre-campaign and campaign periods as new polls are published.

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