Trends over time
A question series is the same item, asked repeatedly by the same organization. These are the only comparisons in this archive that can honestly be drawn as a line.
Why the bar is this high. Grouping different questions on a topic and plotting the average produces a line
that mostly tracks which pollsters happened to field that year. A series here requires near-identical wording from one house
and at least three separate fieldings on different dates — several items asked in one wave, or the same item asked in four
states at once, are a battery rather than a trend. Where a series crosses a change in survey mode — live-caller telephone to online panel,
an industry-wide shift over this period — the chart says so, because part of the movement may be the method rather than the public.
Each point links to the poll it came from. How to read this data →