Lab 11 / Communication

The same values on two axes

How much can a narrow baseline magnify an unchanged difference?

6 min synthetic data fixed seed

Place five synthetic rates on a full and focused scale, then measure how axis limits change visible distance without changing the data. Change one control at a time, then open the values under the chart before interpreting the picture.

Interactive synthetic lab
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View the values behind this chart

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SEED

What this display answers

The numerical rates never change. Only the mapping from values to vertical distance changes when the focused minimum moves.

A zero-based bar uses length to represent the full magnitude. A truncated bar represents only the distance above the cropped baseline, so its visible ratio can exaggerate the comparison. A focused line can be useful when exact values and scale limits remain explicit.

What to notice

  1. Compare the same five labels in the full overview and focused panel.
  2. Raise the focused minimum toward 98%. The reported amplification rises while the numeric range stays 0.6 percentage points.
  3. Switch between bars and a line. The encoding changes what viewers naturally compare, even though the coordinates are identical.

The model behind it

Five fixed synthetic pass rates range from 98.1% to 98.7%. Both panels use linear scales with a maximum of 100%.

Amplification is the full 100-point axis span divided by the focused axis span. It describes pixel mapping, not practical importance or evidence of a real change.

Where the result stops

Axis choice cannot repair inconsistent denominators, irregular time spacing, or missing uncertainty.

A focused scale may clarify a line pattern, but it should not be used to imply a larger absolute effect than the labels support.