Lina's Channel ROMI — Schema
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Flat CSV in lina-channel-romi.csv. One row per channel.

Columns
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Column               Type     Description
-------------------  -------  ------------------------------------------------------------------------------------------------------------------------------
channel              text     Marketing channel name (Paid Social, Email, Search, Content, Display).
leads                integer  Total leads generated by the channel in the reporting window.
cost_per_lead_usd    integer  Blended cost per lead in USD.
conversion_rate_pct  decimal  Lead-to-customer conversion rate as a percentage.
romi_ratio           decimal  Return on marketing investment as a ratio (revenue attributed / spend). Values above 1.0 are profitable; below 1.0 lose money.

Row inventory
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- 5 rows — one per channel.

Total: 5 rows.

Deliberate design choices
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The dataset carries all four metrics per channel so the reader can reproduce Lina's original clustered-column chart (which plots leads, cost per lead, and conversion rate across three incompatible axes) as well as the single-encoding rebuild (which uses only romi_ratio). Keeping all four columns visible makes the contrast tactile: the reader can see that only one of the four metrics answers the VP's Q4-spend question, and that all four columns being present is exactly why the clustered column fails.

romi_ratio is quoted to two decimals to match the Big Idea's exact wording ($3.40, $0.80). Any downstream chart that displays these values matches the print figure exactly.

License
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Released for teaching use alongside The Defensible Decision. Use freely.