Show the second-place margin in tooltips on winner maps
For interactive inspection of winner-take-all district maps, use tooltip text on choropleth maps to improve insight and address winner-only summaries for readers checking how close the top two candidates were.
- purpose:refine
- basis:heuristic
- chart:choropleth
- data:geospatial
- component:tooltip:use
- operator:difference
- quality:insight:use
- lever:interaction-access
advice
Add the runner-up margin to the tooltip
Put the second-place margin into the tooltip on winner-take-all district maps. For example, on a map of district winners, add the vote difference between the winner and the runner-up to the hover text so close races can be found.
reason
Why the runner-up margin works
A winner-colored map hides how narrow the victory was, but the tooltip can reveal whether the first and second candidates were far apart or nearly tied.
Mechanism: Adding the gap between first and second place turns a winner-only map into a map that also supports inspection of close contests.
Evidence: The post says that one of the more interesting aspects of a first-vote winner map is the margin for the second-place candidate and describes adding that information to the tooltip because winner and runner-up shares are fairly close in some districts (Muth, 2021).
context
Use when the map shows district winners
- User Goal: Let readers inspect how close district-level wins were.
- Task: Compare the winner with the runner-up within a district.
- Data: Winner-take-all district results with identifiable first and second place.
- Chart Setting: An interactive map with hover tooltips.
- Success Criterion: Readers can discover narrow wins without changing the main winner map.
exceptions
Do not use when the map is not a winner view
Break it when: The map is not showing winner-take-all district winners. Why: The post introduces the second-place margin specifically as extra detail for a first-vote winners map.
costs
Tradeoffs of the tooltip detail
Sacrifice: The second-place margin is hidden until interaction. Risk: A reader can miss close races without hovering over districts. Mitigation: Keep the winner visible in the main map and reserve the margin for the tooltip detail.
mistakes
Common failure around the tooltip detail
Mistake: Show only the winning party in the tooltip. Why it fails: The map still hides whether the race was close.
check
Check whether closeness is visible
Failure Sign: Hovering a district shows the winner but not the gap to second place. Quick Check: Hover a close district; if you cannot tell how narrow the win was, the tooltip is missing the key comparison. Stronger Test: Verify that the hover detail includes information for both first and second place or their margin.
fix
Fix the winner-only tooltip
- Add the vote difference between first and second place to the tooltip.
- Include runner-up information alongside the winner in the hover detail.
- Keep the main map focused on winners and move the closeness detail into the tooltip.