| Verified against primary record | |
| What seasonal adjustment does | Filters out usual seasonal fluctuations and typical calendar effects from a time series[1] |
|---|---|
| Four different measures | Two-month share, Gini coefficient, seasonal deviation and the peak to low ratio[2] |
| Tourism benchmark | July and August accounted for 31 per cent of annual nights spent in EU tourist accommodation in 2025[2] |
| Records read | Seasonal adjustment guidelines, a seasonality article, a regulation, a statistical release and a metadata record, 9 October 2026 |
| Independently reported | |
| Why general tourism is seasonal | Climate and geography, together with social and cultural factors such as school holidays[2] |
| Bands apply only to the rows beneath them. The tourism figures are not medical figures and are given as context only. | |
Seasonality in medical tourism is widely asserted and, on the evidence located for this entry, not measured anywhere. The statistical machinery for measuring seasonality is well developed and is applied to tourism in detail. None of the collections that identify medical travel publishes data at a frequency that would reveal a seasonal pattern.
What seasonality means in statistics
European statistical guidelines define seasonal adjustment as filtering out usual seasonal fluctuations and typical calendar effects from a time series, where usual seasonal fluctuations are those movements which recur with similar intensity in the same season each year.[1] The definition requires several years of sub-annual observations to establish what is usual, which is the first obstacle in this field.
Seasonality is also not one number. Eurostat’s own article on tourism seasonality sets out four distinct measures: the share of nights falling in the two dominant months, a Gini coefficient comparing the cumulative monthly distribution against a uniform one, a seasonal deviation defined as the average of the absolute deviations of monthly data points from their annual mean, and the difference between the peak and low month expressed as a ratio.[2]
The agency flags the trade-off between them, noting that the two-month share is more intuitive for users but can be affected by extreme values in the peak months.[2] Different measures can rank the same countries differently, so any seasonality figure needs its measure named.
What general tourism seasonality looks like, and why it may not transfer
For a benchmark, July and August accounted for 31 per cent of all annual nights spent in European Union tourist accommodation in 2025, close to a third of the year’s nights in two months.[2] That figure is for 2025 and should not be mixed with the higher share reported for the pandemic-affected years.
The drivers matter more than the number. The same article records that many tourist activities have always been highly seasonal, with the leading reasons being environmental factors such as climate conditions or geographical location, together with social and cultural factors such as school holidays.[2]
Neither driver is obviously a driver of elective surgery. Weather does not determine when a hip needs replacing, and school holidays bear on family travel rather than on a patient travelling for a procedure. Any transfer of general tourism seasonality to medical travel is therefore an assumption rather than an inference, and this entry does not make it.
The structural reason it cannot be measured
European tourism data exists at monthly frequency and is legally mandated, with the governing regulation requiring monthly transmission of nights spent, arrivals and occupancy rates by accommodation class, within six weeks of the end of the reference period from reference year 2022.[3] That monthly collection carries no purpose of trip.
Purpose of trip sits in a different part of the same regulation, as an annual tourism-demand variable, and health treatment appears there only as a parenthetical example inside a residual personal-travel category.[3] So the frequency and the purpose exist in the same statistical system and never in the same table.
The nearest thing to a sub-annual series containing health travel is one national passenger survey, which publishes quarterly results, states that its main series are seasonally adjusted to identify seasonal patterns and calendar effects and remove them from the unadjusted data, and reports visits for health inside a miscellaneous category alongside study, sporting events, shopping and religious purposes.[4] Health is seasonally adjusted there, and is not separable.
The collections that do identify medical travel are annual by construction. European hospital discharge statistics use the calendar year as the reference period and are normally released in December.[5] The one national medical tourism collection located for this site carries individual years as its time dimension. Neither can show a within-year pattern.
What that means for seasonality claims
Claims that a destination has a high or low season for medical travel rest on provider booking data or on inference from general tourism patterns. The first is provider-supplied and unaudited; the second assumes drivers that the tourism statistics attribute to climate and school holidays. Neither is a measurement, and a seasonally adjusted series of medical travellers does not appear to exist in any collection reachable for this entry.
There are plausible reasons seasonality might exist, including surgeon availability, local public holidays, airfare cycles and recovery weather. None of them has been tested against data here, and they are listed as hypotheses rather than findings.
See also
- Medical tourism patient flows, what directional data exists at all
- Air connectivity and medical tourism, the other travel-side variable commonly asserted
- Medical tourism statistics, the frequency and coverage of what is collected
- Medical tourism market forecasts, projection method and its limits
References
- Eurostat. ESS guidelines on seasonal adjustment. 2015 edition, Publications Office of the European Union. Verified against primary record: the definitions of seasonal adjustment and usual seasonal fluctuations were read in the introduction. A later edition exists and was not retrieved. Retrieved 9 October 2026.
- Eurostat. Seasonality in the tourist accommodation sector. Statistics Explained, data extracted May 2026. Verified against primary record: the four measures, their trade-offs, the two-month share and the stated drivers were read. Retrieved 9 October 2026.
- European Parliament and Council. Regulation (EU) No 692/2011 concerning European statistics on tourism, Annexes I and II. Consolidated text as at 31 January 2020. Verified against primary record: the monthly transmission requirements and the annual purpose-of-trip variable were read in the consolidated text. Retrieved 9 October 2026.
- Office for National Statistics. Overseas travel and tourism, provisional results. Released 19 January 2017. Verified against primary record: the quarterly basis, the seasonal adjustment statement and the miscellaneous purpose category were read. Retrieved 9 October 2026.
- Eurostat. Hospital discharges and length of stay, ESMS metadata, hlth_hosd. Metadata last updated 15 December 2025. Verified against primary record: reference period and release timing read. Retrieved 9 October 2026.
Sourcing note: the seasonal adjustment guidelines, the seasonality article, the tourism regulation, the passenger survey release and the hospital discharge metadata were opened and read on 9 October 2026. No monthly or quarterly series of medical travellers was located in any collection consulted, and that is stated as the result of searching rather than as proof that none exists. The tourism seasonality figures are for all accommodation nights and are not medical figures. The possible drivers listed at the end are hypotheses and are labelled as such. The seasonal adjustment guidelines are cited from the 2015 edition; a later edition exists and was not read.