Google Trends provides access to the search requests made to the Google search engine by its users. In particular, Google Trends contains a random sample representative of all queries that Google handles daily.

The analysis is performed using search data available through the Google Health Application Programming Interface (API), which provides access to information on a representative sample of searches performed on the Google Search engine. The Google Health API returns information normalised to the time and location of a query. By time range (weekly in this report) and geography (country or regional level) each data point is divided by the total searches to obtain relative popularity. This provides advantages over the usage of Google Trends data which, after being rescaled are also normalised on a 0 to 100 scale. However, results shown in this report do not represent the absolute volume of searches, but rather their volume relative to the total amount of searches. Changes over time for a particular search term could therefore be driven by changes in the absolute search volume, changes in the volume of other searches or a combination of the two.

In addition, google returns also top related searches and topics. Top searches are terms that are most frequently searched with the term users enters in the same search session within the chosen category and geography. Topics, which have started being available starting in late 2013 in the US and in the following years in EU countries, are instead aggregations of different queries related that could be assigned to a particular topic. Aggregation is done by Google using semantic integration algorithms in the context of the Google knowledge graph. This approach has a few advantages over the usage of queries.

To select the topics included to create the indicators contained in this report, the JRC adopts both a data-driven and data-informed approach. First, JRC researchers selected a few topics related to the policy areas of the European Green Deal, i.e., Air pollution, Renewable energy, Electric vehicle, Recycling, Organic food. These topics are then used as a seed to retrieve all topics linked to them. Then the retrieved topics are used as a seed themselves to retrieve all related topics. This procedure
resulted in a list of more than 2 000 topics. Using a data-informed approach, the JRC then selected only those topics relevant in the context of the European Green Deal while organising them according to the theoretical framework that is presented in this report. While this approach has clear advantages, some caveats apply. First, while searches are informative for the population in the working age and about 90% of EU households have internet access, younger individuals are more likely to use the internet than the elderly. Further, access to the internet is not random with respect to socio-economic status. Maps scales are based on quartiles of the distribution of the variable of interest. EU-27 averages are population-weighted.