THE RESULT
What the data shows
The largest computed metric is 1.067e+07 for Retain source repeats; the smallest is 8.911e+06 for Known customers only. Metric: gross_gbp (GBP).
Unknown customers and repeated lines are different quality issues; neither is automatically an invalid sale.
| policy | rows | gross gbp | difference from retained gbp |
|---|---|---|---|
| Retain source repeats | 530,104 | 10,666,684.54 | 0 |
| Remove exact repeats | 524,878 | 10,642,110.80 | -24,573.74 |
| Known customers only | 397,884 | 8,911,407.90 | -1,755,276.64 |
THE METHOD
From source to answer
Compare retained source rows, exact-row deduplication and exclusion of unidentified purchasers.
The Python source exposes this study’s transformations. The complete project download includes shared preparation and evaluation routines.
THE NEXT DECISION
What follows from the finding
Choose cleaning rules from source-system evidence and document their financial effect.
Where the conclusion stops
Historical invoice lines; credits are not reliably matched to original sales. Gross purchases are not profit. Unidentified customers cannot support customer-level conclusions. Exact repeated lines remain unless the study explicitly compares removal.
Related studies may reuse observations or holdouts. These are historical analyses; associations and backtests do not demonstrate commercial impact. Further model tuning needs new, untouched evaluation data.