Another thing you can't do in PubMed, but you can do in OvidSP is "Adjacency", or "Proximity Search". In general, requiring two or more query terms to be near each other usually retrieves records that are more relevant. The operator "ADJ" is known as the "Positional Operator", which lets you to retrieve records that contain your search terms within a specific number of words of each other. For example, the search "physician adj5 relationship" retrieves records that have the two terms no more than five words away from each other, or, another way to put it, no more than four words between them, and this could be in any direction. So any records that contain phrases such as "physician patient relationship", "patient physician relationship", "relationship of the physician to the patient" will be retrieved. You can, of course, combine the positional operator with truncation and wildcard symbols. So if I say "patient dollar sign adj2 educate dollar sign" it'll retrieve records that have "patient education", "educating patients" or "educating cancer patients" as matching records. You can combine adjacency search with a field search. For example this search: "opening parenthesis physician adj3 relationship closing parenthesis dot ti dot" retrieves records from the title field that contains any phrases in which the term "physician" and "relationship" are within three words of each other. In general, records that contain many instances of your search term are more relevant than those that contain fewer instances. The frequency operator "FREQ" lets you specify how many times a query term must appear in a record in order for the record to be retrieved. Because word frequency is only indexed at the field level, you're required to qualify your term to a specific field when doing a search with frequency operators. For example, the search "blood pressure dot AB dot slash freq equals ten" retrieves only records in which the phrase "blood pressure" appears ten or more times in the abstract field. For the same reason, the frequency operator cannot be used with multiple fields, or with a field that consists of multiple fields, such as the source field, "SO", the text word field, "TW", or the multiple places field, "MP". So "blood pressure dot TI comma AB dot slash frequency equals three" will result in an error message. You can combine adjacency and frequency searches in the same query. For example, "opening parenthesis physician adj3 relationship closing parenthesis dot ab dot slash frequency equals five" retrieves records in the abstract field that contain any phrases in which the word "physician" and "relationship" are within three words of each other, and occur at least five times in the record. Just as PubMed, OvidSP also supports standard Boolean operators "and", "or", and "not". They can be used to combine a list of search terms to create a query that represents a single concept, or they can be used to combine existing queries. Let me clear my search history here... So I can say "exp hypertension slash or high blood pressure dot mp dot or hypertens asterisk dot mp dot". And I can say "exp angiotensin converting enzyme inhibitors slash or ace inhibitor dot mp dot". Of course, in a real search for systematic review, you would type in all the synonymous terms in here, but for demonstration terms, this is enough. You get the idea. You can see that my search each got a set number, and I can combine them with "and", so "one and two". Unlike PubMed, you don't need to use the pound sign to indicate the set number. Now, if I don't want anything that's a letter, I can say "opening parenthesis one and two closing parenthesis not letter dot pt dot". Of course, you can also use this interface to combine queries with Boolean operators, so select the rows you want to combine in the search history table, and then use these Boolean operator buttons to combine them. OvidSP provides limit options for your search results similar to those in PubMed. So if I want to limit my last result set to the articles published in 2000 and later, I can say "limit to year equals 2000 to current". If I want to further limit the set to English language and humans, I can say "limit to opening parenthesis English language and humans closing parenthesis". There are these quick limits in the search interface down here - this will only apply to the current search or the last row in the search history table. You can also see more limits by clicking on the "Additional Limits" button and in here, you not only have more limit options, you're also free to choose a search other than the last row in a search history table to apply the limit to. So in this video, we demonstrated the same search concepts we introduced in a previous video with OvidSP MEDLINE as the example database. We particularly looked at OvidSP's unique command line query syntax, which has a little bit of a learning curve, but ultimately it'll help you run your search faster. We also looked at some additional search concepts not available in PubMed, such as "Positional Operator" and "Frequency Operator". Both PubMed and OvidSP MEDLINE implements a controlled vocabulary system, however there are also a lot of other databases that do not have a controlled vocabulary system, and some of them are quite popular. I'll show you how to build search strategies in those databases in the next video using the Web of Science and Scopus as examples. I'll see you next time.