Who counts us? Mobile phone data, cruise tourists and the question of transparency

Who counts us? Mobile phone data, cruise tourists and the question of transparency

Key question: Can anonymized mobile signals really provide reliable answers — and who later decides what happens with those findings?

Critical assessment

The Balearic tourism agency plans to analyse movements of cruise guests using anonymized mobile phone data. It concerns three months in 2025 — February, July and October — and the roughly 1.4 million cruise passengers who used the Port of Palma in 2025. In Palma, data will be evaluated by about 290 counting zones, while for the rest of Mallorca it will be done at municipal level. The measurement points: signals that phones send to masts, handovers between cells, sampled at intervals of up to 15 minutes. On paper this sounds like clean science. In reality, such procedures are fine craftsmanship and full of pitfalls.

What pure technology does not show

Mobile network data say something about signals, not about intentions. A device registered in a historic town house can belong to a day visitor or to a resident. The tender conditions demand that each person be counted only once and that different visitor groups be separated — day arrivals, cruise passengers returning to the ship, guests with accommodation on the island. Much of this depends on criteria, thresholds and assumptions that will later be embedded in the report. Small differences in network coverage, mobile operators, certain phone models or behaviour (turning off roaming, airplane mode) can noticeably change the results.

What is missing from the public debate so far

Public discussion often focuses only on the headline: more data, better planning. But three important points are rarely negotiated: First, how transparent is the methodology? When authorities present figures, local municipalities, shop owners and residents should understand how those figures were produced. Second, who has access to raw data and analyses? An anonymized delivery sounds reassuring, but without independent review trust remains fragile. Third, what consequences will be drawn from the numbers? Will timetable changes, visitor management or new fees be prepared — and on what democratic basis?

A day-to-day view of Mallorca

On the Passeig Marítim there is the smell of oil from small snack stands, street sweepers brush cigarette butts into the gutters and tour groups mix with school classes. When four cruise ships are in port on a morning, La Rambla and the alleys around Mercat Olivar fill within an hour. Voices, the clicking of camera shutters, the rumble of suitcase wheels — all of that is visible, but not always measurable. This is exactly where the practical difficulty begins: crowds follow social patterns, not just radio masts.

Concrete approaches

Those who want reliable, accountable findings should do more than buy data. Proposals that could prove effective in our practice on Mallorca:

1. Disclosure of methodology: The agency should publish the computational model, the assumptions about counting rules and the margins of error before results are used as a basis for decisions.

2. Independent review: An independent body of technicians, data protection experts and representatives of the municipalities must be given access to the processes and be allowed to carry out plausibility checks.

3. Hybrid approach: Combine mobile data with classical methods: on-site samples, traffic counts at key points, anonymous Wi‑Fi and Bluetooth measurements as well as surveys of local businesses.

4. Data minimisation and deletion deadlines: Store only the necessary aggregation levels, limit time windows and set clear deletion deadlines.

5. Local involvement: Results should be available to municipalities in interactive dashboards. Small places like Port de Sóller or Cala Millor need different measures than Palma city centre.

Concise conclusion

Technology can finally show us better where tourist pressure arises — but only if figures are produced with care, oversight and transparency. Without these ingredients a useful measurement method quickly becomes an instrument that justifies decisions instead of questioning them. On Mallorca, where a street, a market and a park are immediately tangible, it is not enough to present numbers. We need a public debate about the methods, comprehensible results and clearly named measures that should follow from the data.

In the end, the people on the island must decide how they want to be counted — and under what conditions.