For instance, using Ovid for Medline searches, can I simply explode the MeSH heading 'Education' to include all its narrower terms, for example Curriculum, Distance Education and Nonprofessional Education, or do I need to manually select each one and explode them so that my search includes all their narrower terms in turn?
The example used for this question will be a Medline search on Ovid, but the principle applies to most subject searching databases that we subscribe to.
The first image attached at the bottom of this page, 'MeSH headings', shows you the entire structure of terms indexed under 'Education'. If we look at it closely we will see that only 20665 articles are indexed under 'Education'. However, the same heading has a lot of other narrower terms, many of them, such as Curriculum, with their own narrower terms; Competency-Based Education, Interdisciplinary Studies, Education Mainstreaming and Problem-Based Learning.
Will exploding 'Education' automatically include the 74106 articles under Curriculum, but also 3903 articles in Competency-Based Education, 1051 in Education Mainstreaming and so on?
The answer is 'Yes'. As you can see in the second image attachment 'Results' there are three searches for Education:
As long as you are happy to include all the terms within a broader MeSH heading, exploding it will do that job for you. You would probably go through the terms individually if there were many of them and some of them were definitely irrelevant to your search. This would reduce the number of articles you are screening, but it is a choice you have to make.