Choosing Trend Or Slope View

Choosing a trend line vs a slope view

"How did X change between A and B?" is ambiguous. Two charts answer two different

questions, so clarify before you build unless the user already named one:

• Change over time (line) — the value at every interval across the range.

Shows the _path_: dips, spikes, when it moved. This is the default trend.

• Start vs end (slope) — only the first and last point, one line per series

connecting them. Shows the _net change_ and, across many series, which rose,

which fell, and any rank flips — without the noise of the path between.

When the request could be either, ask a short either/or, e.g.:

> Do you want to see how it moved across the whole period (a line chart), or just

> the change from the start to the end (a slope chart)?

If the user clearly wants one — "just tell me how much it grew start to end" → slope;

"show me the trend / when did it spike" → line — skip the question and build it.

How to render each

Both come from the same TrendsQuery over the same date range — the slope is

that series collapsed to its first and last point, not a different query.

Change over time → line

Default trends behavior. Create or run a TrendsQuery and leave

trendsFilter.display as ActionsLineGraph (the default, "change over time"):

{
  "kind": "TrendsQuery",
  "series": [{ "kind": "EventsNode", "event": "$pageview", "math": "total" }],
  "dateRange": { "date_from": "2025-01-01", "date_to": "2025-03-31" },
  "trendsFilter": { "display": "ActionsLineGraph" }
}

Start vs end → slope

Run the trend with posthog:query-trends. The result card Max renders has a

Line / Bar / Slope view toggle — switch it to Slope to show each series as

a single line from its first to its last point, with the per-series change in the

legend. Tell the user they can flip to the Slope view on the result.

The slope view is best for a clean before→after comparison, especially with several

series/categories whose relative movement matters. Pick a date range whose two ends

are the points you want compared (the slope uses the first and last interval).

Important limits

• Two surfaces, one computation. Both the inline slope (Max's query-trends

result card) and the saved-insight slope (ChartDisplayType.SlopeGraph, behind the

slope-graph-insight feature flag) show the same thing: the first interval's value

vs the last interval's value, at the chosen group-by interval. The grouping defines

the slope — group by month to compare the first vs last month, by day for the first

vs last day. Use the inline view for a quick before→after on a result you're already

looking at; reach for the saved display to persist it on a dashboard where the flag

is enabled. A still-accumulating final period is shown as-is with a dashed connector,

the same affordance the line chart uses for an incomplete tail.

• For period-over-period on a single series (this month vs last), a line with

compareFilter: { "compare": true } overlays the two periods; a slope is the

better fit when comparing the endpoints of many series at once.