StatsWales

At the end of 2025, the Welsh Government launched a revamped data platform making it easier to explore and create tailored datasets. The new StatsWales is designed for ongoing, granular data exploration, with interactive menus and tables to generate curated datasets straight from the platform. 

The site features a wide variety of geographic boundaries. While most data is published at the health board and local authority levels, select releases are available by constituency.

DataMapWales

DataMapWales is a resource built specifically for location-based visualisation, offering geographic datasets to map layers, explore boundaries, plot facilities, or extract spatial data. Besides geospatial boundary data, the platform also includes niche datasets, such as GP practice locations, rainfall patterns, and air quality metrics.

Public Health Wales

The NHS Wales network hosts a variety of health data dashboards offering extensive breakdowns on disease prevalence and health services by demographics and geographies. This helps inform care and provides key information on the performance of health services across Wales.

Other databases

Although the above sources provide the majority of datasets covering Welsh geographies, UK-wide open data platforms are a good source of alternative releases:

• Census 2021: Wales conducts its Census survey alongside England. The Office for National Statistics hosts an open data dashboard offering both standardised and custom datasets displaying the Census results by a variety of boundaries, from Westminster constituencies and local authorities to Welsh health boards and Senedd constituencies. The 2021 Census surveyed populations across England and Wales on education, employment, health, demographics, and Welsh language skills.
• Office for National Statistics (ONS): The ONS includes many datasets covering all UK nations, from Labour Market figures updated monthly at the local authority level, to mortality and social care data.
• Gov.UK: Similar to Gov.Wales, Gov.UK is the main source of open data for the whole of the UK, hosted by the UK government. This site includes a release calendar displaying datasets published across government departments by date, covering non-devolved topics that apply to Wales.

How to adapt geographic boundaries

Despite the large availability of datasets representing a variety of Welsh geographies, data published at the Senedd constituency level may not be readily available for your chosen topic. That is why a common next step is applying data conversion methods. Whether you are struggling to find Senedd constituency data or your required data is only available at the local authority or health board level, one of the methods below can help.

Data assignment

Data assignment processes offer a quick turnaround to create constituency outputs for MS engagement.

Taking local authority data as a starting point and using an overlap analysis, determine which Senedd constituency a local authority sits in. Due to the large size of Senedd constituencies, most will overlap with multiple boundaries; however, a specific local authority will often occupy the majority of the constituency footprint. This analysis identifies which boundaries occupy the most space in a given constituency and simply allocates the respective data point, avoiding complex data modelling.

Data conversion

Alternatively, an overlap analysis coupled with population data can be used to produce Senedd constituency-specific data. While this method requires more complex data modeling, it delivers greater granularity to the final outputs.

Starting with a similar spatial analysis, determine the geographic overlap between both boundary levels and combine this with local population figures to establish a weighting multiplier. For absolute counts, apply this multiplier to the original data and aggregate the transformed data points to derive a constituency total. For rates, assign the exact value when there is a single boundary overlap or calculate a weighted average when spanning multiple boundaries.

Additionally, because UK Parliament constituencies fit neatly within the new Senedd boundaries, a simplified conversion method can be used when starting from Westminster data. In these cases, absolute counts are simply aggregated, while rates are calculated using a weighted average.

Visualising constituency profiles

Once a final dataset is in hand, visualising it is the last step. Presenting a spreadsheet to an MS is not sufficient. By shaping the data into a compelling message with clear, concise evidential data, your work will come to life.

While there are many solutions available for data visualisation out there, Polimapper can help you build your data dashboards from the ground up. As many MSs look to understand the communities they represent, our data dashboards go beyond visualisation and are tailored to serve as resources guiding parliamentarians through the changes.