METHOD NOTE
What a seizure map cannot prove
An illustrative calculation shows why a rise in seizures cannot, by itself, measure growth in trafficking.
Evidence cut-off: 6 September 2026
Suppose traffickers move 1,000 kilograms through a region and authorities intercept 10%, recording a seizure total of 100 kilograms. The following year, the same amount passes through, but authorities intercept 20%. Seizures reach 200 kilograms although trafficking has not increased.
These numbers are invented for the calculation. They estimate nothing about the Sahel. They show that a seizure total depends on both the amount moving and the share authorities intercept.
Work through the example: why seizures can double
| Year | Amount moving | Interception share | Recorded seizures |
|---|---|---|---|
| 1 | 1,000 kg | 10% | 100 kg |
| 2 | 1,000 kg | 20% | 200 kg |
The seizure count doubles while the assumed amount moving stays level. Real interception rates are unknown here.
The missing denominator
A researcher who knows only the two seizure totals cannot calculate the change in trafficking. The interception share is missing. Treating the increase from 100 to 200 kilograms as a doubling of the market would insert an assumption that enforcement and reporting stayed constant.
A single large load can also dominate an annual total. Reporting both the number of cases and the weight would show that concentration. Neither measure identifies all undetected shipments.
A map adds another claim
A point can mark the broad location of a reported interception. A line joining two points suggests movement between them. To publish that line as a reconstructed route, an editor needs evidence connecting the endpoints within a case.
Separate interceptions may involve different organisations, destinations and years. Putting them on the same map does not resolve those differences. The editor should record the event date and source for each case, then identify any evidence that links it to another.
Location does not identify ownership
Finding drugs in territory influenced by an armed group does not establish that the group owned them. Investigators need evidence of a transaction or other involvement. A payment for passage, possession of a consignment and control of a market are different claims.
An editor can test the copy with three questions: Which event does the source establish? Which people does the evidence connect to it? Does the sentence claim more than that record supports? The answer may require removing a line from the map or a claim from the story.
The accompanying Sahel cocaine article applies these distinctions to dated seizure reporting and UNODC’s assessment. AP’s account of the UNODC document and the copy hosted by InSight Crime repeat the same underlying evidence; they cannot serve as independent datasets.
Sources and method
The numerical example is hypothetical and reproducible. The source supplies background for the linked assessment, not an interception-rate estimate. This note adds no seizure cases or route data.
AI-assisted. Editorial standards.