Embase 2 – Searching with Subject Headings (Emtree)


In this video, I’m going to show you how to search using Embase subject headings, called Emtree. Like MeSH in Medline, Emtree terms are assigned to every article in Embase based on the subject of the article; therefore, using Emtree terms in your search will help you to retrieve more relevant results. To find Emtree terms, ensure the “map term to subject heading” box here, is selected. This will let the database suggest Emtree that it thinks are appropriate based on what you type into the search box. For example, let’s enter the term “iud” in the search box and click Search. In this case, Embase maps our term onto one potential Emtree term, intrauterine contraceptive device, listed here. Sometimes, the term you enter will have an identical Emtree like this; other times, you may have to try a few different options in order to find the best term or terms for your concept. Either way, it’s best to only select one term at a time. You can try to check the scope note, here, for more information, but as you can see, these are not as robust as the scope notes in Medline. Once you locate a subject heading for your term, click on the hyperlink to access the Emtree thesaurus. Notice that our term is highlighted and there are several green lines below. These terms in italics are called Used For terms. Indexers use Used For terms to correctly apply Emtree to records in Embase. For example, if an article is about intrauterine coils or the Dalkon Shield, indexers should tag it with the Emtree intrauterine contraceptive device. This also tells us that Dalkon Shield is not an Emtree, though we still may want to search it as a textword. We can also see other terms related to our Emtree above and below. Terms in italics are Used For terms, while terms with a checkbox beside them are other Emtree. It’s a good idea at this point to explore these terms to determine if any of them are relevant to the concept being searched, for example, intrauterine device expulsion. Here we can see that intrauterine contraceptive device has a Broader Term, female contraceptive device and two narrower terms, copper intrauterine device and levonorgestrel releasing intrauterine system. We know that copper intrauterine device has narrower terms of its own, because of this +NT symbol here. If I click on the term, again here are all of its used for terms, and listed here is its narrower term multiload copper intrauterine device. Its broad term, is of course, intrauterine contraceptive device. Let’s go back to that term by clicking on the hyperlink. To add an Emtree term to your search, you can choose whether to explode the term or not. To explode the term, you can click on the box to the right of your term here, in the explode column. If you choose to explode your term, the database will automatically search for the term you selected, as well as the narrower terms. It will also search for all of the narrower terms belonging to all of the narrower terms. If you don’t want to search for the narrower terms, or you only want to include some of the narrower terms, but not all of them, you can select only the ones you want by checking off the boxes beside each individual term on the left side. Once you have selected the term, and decided whether to search all, some, or none of the narrower terms, scroll back up to the top. Before running the search, make sure that the “combine with” box here on the left is set to OR. This is the default, and we don’t want to change that. Now we can click Continue. Depending on what Emtree you search, Embase may prompt you to select subheadings. Generally for comprehensive searches, we want to include all subheadings and not limit our search further at this point. Click Continue to skip this step. Now Embase has run our search, and we can see that it appears on line one of our search history. You’ll notice there’s a forward slash beside our term as well. This means that the term was searched as an Emtree. You’ll also notice the three letters, exp, at the front of the term, this means that the term has been exploded. It’s good practice to search subject headings on their own line so that it’s easy to read and to make changes later. Try to avoid the common pitfall of rushing through subject heading selection. If you’re not sure what to search, go through the mapping process demonstrated earlier in this screencast, until all options have been exhausted. If you have any questions about Embase please feel free to contact us at [email protected]

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