Use split per-series rows for dispersed cross-series comparisons

Choose split per-series rows when readers must compare series values at different time positions across the span of multiple time series. For example, use small multiples or horizon graphs instead of a single overlaid simple line graph or braided graph for a dispersed cross-series value comparison.

Split per-series rows separate each series vertically, so readers can trace one series across a long span without overlap from the others. That reduces the clutter and long-range line tracing required in shared overlays.

Mechanism: Vertical separation makes dispersed comparisons easier because each series can be followed without interference from overlapping series.

Evidence: Controlled comparisons found the split per-series views faster than the shared-space views for the dispersed aggregate/discrimination-style task, and the collated record ranks the row-based designs ahead of the overlaid designs on time for this task family (Javed et al., 2010; Zeng & Battle, 2023).

Notes: The structured record emphasizes the time advantage for this task; it does not report significant accuracy pairs.

• User Goal: Compare values from different series at different marked time positions.
• Task: Dispersed cross-series comparison over a broad visual span.
• Data: Several series share the same ordered time axis.
• Chart Setting: Static, noninteractive overview view with all series shown simultaneously.
• Audience: Readers making quick cross-series comparisons.
• Success Criterion: Faster completion on dispersed comparison questions.

Break it when: Readers only need to identify which series is highest at one shared time point. Why: Shared-space layouts were faster for the local find-extremum task.

Sacrifice: Split rows weaken direct same-space comparison across series. Risk: Local same-time comparisons become slower because readers must move between rows. Mitigation: Reserve split rows for dispersed comparisons that span different positions or long visual spans.

Mistake: Keep all series overlaid in one shared plot for a dispersed comparison across different time positions. Why it fails: Overlap and clutter make long-range tracing across series slower.

Failure Sign: Reviewers must trace lines through overlap to compare values located at different positions. Quick Check: Compare the current shared overlay against a split per-series version on the same dispersed comparison question. Stronger Test: Time a few readers on both layouts and keep the faster one for that question type.

• Split the series into separate aligned rows for the dispersed comparison view.
• Use small multiples when the comparison can rely on common axes across rows.
• Use horizon graphs when you want the same row-based separation in a more compressed per-series view.
• Remove the shared overlay from the dispersed comparison view.