How to... do an advanced search using Ovid Medline
This guide teaches you how to use the Ovid interface to search Medline, employing the advanced search option. Advanced search allows you to build up different search terms in order to perform a more comprehensive search of a topic. You should use this option if you want to undertake a thorough search of the literature on a topic. If you want to do a very quick search and obtain a general overview of a topic you can also use the basic search option (see How to do a basic search using Ovid Medline). You will need to log in to the BDA website with your web Username (email) and Password to view the OVID Medline web page. To access the page go to www.bda.org/ovid. If you have not logged in before you will need to register using the link on the BDA home page www.bda.org. If you need help to set this up contact the Library on library@bda.org or 020 7563 4545 Overview of Ovid Medline OvidSP is a search interface that provides access to a variety of subscription only databases. The BDA Library currently subscribes to Medline which is a database of biomedical literature and is probably the most comprehensive database of dental articles available. No database covering such a vast topic can contain everything but Medline covers a wide range of medical and health care journals from the US, UK and other countries. Most articles indexed are from English language journals (but do check references are in English but some articles are in a foreign language) and include most of the major English language dental journals and Cochrane Reviews. By using OvidSP to search the Medline database you can export your selected references to a document and set up an account allowing you to save searches. Your search results will be in the form of a list of references. Usually you will not be able to access the full-text of an article, although occasionally a full-text link is available. Please note: Pubmed also searches the Medline database but this is a free interface and users do not need to log in.
Logging on Access to Ovid Medline can be found at www.bda.org/ovid. You must be logged in to the BDA website before accessing Ovid Medline. To access from the BDA homepage go to Library located in the menu across the top of the home page, then to Research and articles on the menu on the left-hand side of the Library home page, then to Ovid Medline on the left. Link to the database from this page and you will be taken to the screen as shown on the right. Tick the second box down as shown (this takes you through to the most up-to-date version of the Medline database) and choose
Using the Advanced Search function You will be taken to the Basic Search page. Click on the Advanced Search link to access. To search for prevention of dental caries in children in this search function you would need to break the topic down. This topic can be broken down into the following three elements: 1. Prevention 2. Dental caries 3. Children The simplest way of doing this search is by doing separate searches for each element and then combining them to bring up a list of relevant references. Type Prevention in the search box. Make sure that Keyword and Map Term to Subject Heading are highlighted. Click on to bring up a list of subject headings relating to the term Prevention.
Searching with subject headings Subject headings are a way of indexing articles from a particular topic under one specific term. Different databases use different subject headings. To find more about each subject heading click on to bring up the term s scope note. Choose the subject heading that most closely matches the topic you are trying to find more information about. In this case we will select Primary Prevention. Clicking on a subject heading takes you to a page showing where this term is listed in Medline s subject heading tree. The term Primary Prevention is listed under the broader heading Preventive Health Services. Immunization is a narrower heading listed under Primary Prevention. To include narrower headings listed under your original subject heading select the Explode box to the right of the broader term (which in this case would be Primary Prevention ). Selecting the Focus box to the far right of a subject heading will search for papers where that term is one of the main topics of the paper. Click Continue to go to the next page.
Subheadings Subheadings are a way of making your search more specific. They are useful if you are searching a topic that has a lot of papers and wish to narrow it down. BUT if you are doing a thorough literature search you may miss useful papers by choosing subheadings. The numbers listed under each subheading show how many papers are listed under that topic. To include more than one subheading in the search select your desired topics. To include papers with either term in your results leave Combine selections with: OR. To include papers which only include both terms use the drop down box to select AND. To include all subheadings either select the box at the top of the page or leave it blank. Click Continue. The first part of the search has now been completed. You should have your heading with number of search results listed on the search history table. Click on Search History if table doesn t show automatically. NOTE: You can remove a search term by highlighting the term s tick box and clicking Remove Selected.
Now repeat the process with the terms dental caries and children. Both these terms have been exploded to include narrower subject headings. For dental caries these terms were root caries and dental fissures and for children the subject heading Child referred to 6-12 year olds. Exploding the term includes the heading Pre-school child. You may want to include extra terms to ensure that the search is as thorough as possible. You could include the subject heading Adolescent to include older children. Including textwords Using textwords will search for terms in the title and abstract of articles and may pick up papers that indexers have not listed under a subject heading you have used. To search prevention as a textword type prevention.tw. as shown on the right.
Combining Keywords To combine search terms to produce the final set of search results you need to understand the Boolean Operators AND and OR. Combining the subject heading Primary Prevention and textword Prevention using AND and OR will produce different search results. Primary Prevention AND Prevention will search for articles that contain both these terms in the same article. Primary Prevention OR Prevention searches for articles containing either (or both) of these terms. So you would need to combine this search in the following way: Primary Prevention OR Prevention select these two keywords (numbers 1 and 4) and press OR to combine. This produces result number 5. As we want Medline to search for articles containing both Dental Caries and Child and at least one from Primary Prevention and Prevention we now combine search numbers 2, 3 and 5 with AND.
Limiting a search To reduce the number of search results you can restrict your search by clicking on Limits under the search box. Selecting the limit English language or just, Selecting English language will remove any articles written in any language but English, for example. You can also restrict your articles to a specific date range in this section. Click on Search to apply the limits from this section to your search. Clicking on allows you to further focus your search by journal type (including dental journals) and publication type (comparative study, review, letter etc), amongst others. Click on from this section. when you select limits
Understanding search results Each individual search result lists the article title, author, journal title, date and type of publication (eg. journal article, comparative study). Clicking on Abstract Reference or Complete Reference gives you further information including the abstract of an article (if available), and the subject headings the paper has been indexed under. Exporting search results To create a document of your chosen results first choose if you want to export all references in your search results by clicking the All box or entering the numbers of the papers you want in the box to the right of this (i.e. 1-20 or 1,3,6,7). You can also make your selection by ticking the boxes next to the reference number of your chosen titles. Click on Export.
You will be taken to a page with a box like the one on the right. You can choose what information you want to include in your list and the final format such as Word, pdf etc. In the Select Fields to Display section choose how much of the reference you want to include. Ticking the Include Search History box will include your search strategy on the top of your list of references. It s often a good idea to tick this box to ensure you have a record of how you conducted the search. Shortcuts Each Medline record is made up of a number of individual fields most of which are searchable. This list is a selection of the most useful codes for looking in particular fields. For example, orthodontics.ti. searches for articles with the word orthodontics in the title. All search field codes are listed under the Search Fields tab..au. author.jn. journal title.mp. multiple posting (abstract, title, original title, subject heading word, substance name).ti. article title.tw. text word (title and abstract) $ - use to truncate a word eg. periodont$ will search for periodontology, periodontal etc.
Saving searches You can save your own searches to rerun and set up update searches so you can be informed when references are added to Medline on a particular subject. Please see the guide on How to save searches in Ovid for more information. Obtaining articles from the search results The BDA Library provides a document supply service for members. Articles from journals held by the library can be obtained at a cost of 2.50 per paper supplied. For copyright reasons, all requests must be made using a photocopy request form. Other articles can be supplied through our Inter-Library Loan service. More information can found on the BDA website (www.bda.org/library) in the Research and articles section. If at any time you need extra information the Help link in the top right-hand corner of the screen has thorough instructions on using Ovid Medline. BDA Library staff are also happy to undertake a free Ovid Medline search for members. If you have any queries please contact the BDA Library on 020 7563 4545 or library@bda.org