Research categories in Dimensions represent areas and topics of scientific research and can be as broad as "engineering" or "chemistry", or as specific as certain types of diseases like "emerging infectious diseases" or "health effects of indoor air pollution".

Within Dimensions, we have embedded a number of classifications systems (sets of research categories), and over time we will increase the number and scope of these. There are a number of advantages of using pre-existing classification systems:

• You can use them in conjunction with keyword and abstract searches, or other classifications systems. For example, if you run a search for salt OR sodium and filter to HRCS > Cardiovascular you will only return grants or publications that fall into the "cardiovascular" set as defined by HRCS but also include the terms "salt" or "sodium". This means you don't always have to create a complete, complicated query when looking for specific results.
• They are maintained by subject matter experts; governance is externally controlled.
• They generally have guidance topics for usage. For example, the precise meaning and scope of a term and rules governing the number of terms per grant, meaning you know what to expect from returns.
• Their usage is often already quite extensive.

How are the categories created?

Standard categories are built in Dimensions using emulations of the categorisation systems led by machine learning. This is done by taking a set of documents coded by subject matter experts in that system, and then feeding these into the Dimensions machine learning algorithm, before then using what the system has learned to automatically categorize new documents. The algorithms are refined through identification of false positive and false negative allocations, and once a high enough level of accuracy has been achieved these definitions are then used in Dimensions to automatically label all information coming into the system. This means that categories can quickly and easily be used to search Dimensions or filter any list of results from a search.