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The triage plane

Description

The fifth component of effector's report: the triage plane. Every feature as one point, importance against heterogeneity, and one arrow per accepted split. Where to look first.

Reading time

Approx. 4' to read.

What you see

The Overview section of the HTML page draws every supported feature on two axes, both in the output's units:

The feature triage plane

From the report embedded in the guide's map, the default nof_instances=10_000 run.

  • x, importance: how much the feature's mean effect moves the output.
  • y, heterogeneity: how much the per instance effects spread around that mean.

Reading the quadrants

quadrantChart
    x-axis Low importance --> High importance
    y-axis Low heterogeneity --> High heterogeneity
    quadrant-1 Your to-do list
    quadrant-2 Noisy, but weak
    quadrant-3 Ignore
    quadrant-4 Done, the mean effect is the whole story

Bottom left is ignorable. Bottom right is important and fully described by its mean effect: read the curve, done. The top right corner, important and heterogeneous, is where the mean hides something: that is where the regional analysis goes hunting. In the figure, hr sits alone in that corner.

The arrows

An arrow marks each split the decision sequence accepted: from the feature's global point to its instance weighted mean across the subregions. hr starts at heterogeneity 0.48 and lands at 0.29: the split resolved that much spread, and it is the same 0.48 → 0.29 movement the explained variance ledger charges +15.5% for.

Why does workingday have no arrow?

It is the second most heterogeneous feature on the plane, well above the threshold, and the search did find a split for it. But an arrow must be earned: the decision sequence rejected workingday's split as redundant, because hr's split already conditions on it. High heterogeneity gets a feature searched, not accepted; the verdicts live in the rejected splits.

The threshold line

The hairline is heter_threshold: features below it never enter the region search, because there is not enough spread to explain. By default it sits at the median heterogeneity of the supported features; set it yourself in the configuration.

Draw it yourself

The plane is not report only. effector.plot_triage(effect) draws it for any fitted engine, and plot_triage(effect, partitions=...) adds the arrows for partitions you found by hand: see compare and plot_triage.

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