Why do I have to search for subject headings AND keywords? Why not just subject headings, or just keywords?
Answer
Searching for subject headings and keywords goes hand in hand. It is important to search for subject headings because they help capture articles that have been assigned with the same subject heading that we might not have otherwise captured with keyword searching, as sometimes we can't think of all the possible synonyms related to a topic. They're also important to search for because sometimes articles are poorly indexed in databases, meaning there might not be an abstract that we can search in, or a meaningful title.
Similarly, we need to search for keywords because the process of "applying" subject headings to articles can take a while. Though this process is being sped up through the use of AI, it can still take a few months for articles to be properly tagged with subject headings - meaning we have to rely on keywords to capture these types of articles.
In addition, now that AI is increasingly being used to apply subject headings, errors and inaccuracies will occur. This is another reason we can't just search for subject headings - keyword searching is often more precise and will retrieve articles that have either no subject headings applied, or have inaccurate subject headings.