How to use the database command ‘docz.dz.’ to explore your resources on Ovid.

Background

Welcome to the first module of the training orientated, search filter examples on OvidGO! / Focused Searches. This Focused Search is a single command, single line search whose task it is to display all the records in the database you have selected. A simple, powerful and empowering search, it will enable you to narrow your focus and burrow down into the constituent parts of the database you are looking at, as well as cast spotlights on its detail. Or alternatively, you could widen your focus and draw back, to compare the relative sizes of a combination of databases you are considering to use.

The docz.dz Command
Entered at the command line in any of, for example Ovid MEDLINE’s search modes, the docz.dz command will search for, and display, the number of records in the resource at that particular moment in time. The docz.dz command can be used on any database on Ovid as well as on combinations of databases. In the graphic below, for instance, the docz.dz command was used to establish the total number of database records in a selection of user-defined resource categories.

The table below indicates the exact number of records retrieved on the day and time of investigation.

For the active links behind the verification searches, please refer to the Supplemental Information for the Focused Search: Databases on Ovid (Resources) – All Databases.

Practice Suggestions

1. Logon to Ovid, select Ovid MEDLINE <1946 to Present> as your database resource and enter docz.dz at the Basic Search or Advanced Search command line. Display the first reference. When was it published? What type of document is it? For example, an article, an editorial, or a conference abstract? How can you tell?
2. Use the Go to result option to locate and display the very last reference. When was this reference published? What type of document is it? Does it have an abstract? Does the previous reference to it have an abstract?
3. Use docz.dz to establish the number of records in the other Ovid databases your institution has subscribed to, for example, Embase on Ovid, APA PsycInfo, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Register of Controlled Trials (CENTRAL), KSR Evidence etc.  

Strategy

docz.dz.

How to use the database command 'docz.dz.' and the Status (ST) field to identify the constituent parts of Ovid MEDLINE and show their relative sizes.

Background

This Focused Search establishes the number of records in the Ovid MEDLINE database as well as the status of those records at the time of the executed query. Database records enter the database via different routes. They move through a series of editorial processes and quality control checks and are only accorded MEDLINE status upon completion of those checks.

A record with MEDLINE status will have had MEDLINE’s proprietary medical subject heading terms, the so-called “MeSH terms” allocated to it. Knowing this has important consequences for how you build a search. Some 14% of the records in the database do not have MEDLINE status and so will not be captured using a search that only relies on MeSH thesaurus terms. Also, some limits, for example the Publication Type, Randomized Controlled Trial (randomized controlled trial.pt.) or Age Groups, All Adult (19 plus years) only operate on MEDLINE status records.

Noteworthy here is that the Status (ST) field, deployed as a limit, makes no mention of books. Books as a type of database record is accounted for by #7 in the search strategy, so that the number of records produced by lines #1 and #8 are the same. See below the attached reference Ovid's Medline Compared To PubMed (Ovid Knowledge Base) for details.  

The docz.dz Command
Entered at the command line in any of Ovid MEDLINE’s search modes, you can use the docz.dz command on any database on Ovid to establish the number of records in the resource. By combining this database command with database fields such as Status (ST) or Publication Type (PT), either individually or in combination, it becomes possible to imagine the ‘shape’ of the database. By this is meant the database’s structure, its composition in terms of database fields, its indexing processes, controlled vocabulary and limits options. These are database properties you need to know, be aware of  and consider when designing search strategies as they may have a material impact on your searches, their construction, execution and rendered outcomes.    

Practice Suggestions

1. Calculate the percentage of PubMed-not-MEDLINE records currently on Ovid MEDLINE.
2. Use the docz.dz command to establish the number of records in the other Ovid databases your institution has subscribed to, for example, Embase on Ovid, APA PsycInfo, Cochrane Database of Systematic Reviews (CDSR), Cochrane CENTRAL Register of Controlled Trials (CENTRAL), KSR Evidence etc.  
3. Run the following docz.dz based search for Embase on Ovid. What does the result tell you about the ‘shape’ of Embase on Ovid? < Click here to run search >. Try also, 

• APA PsycInfo < click here >
• Food Science and Technology Abstracts < click here >
• Cochrane Database of Systematic Reviews (CDSR) < click here >
• Cochrane CENTRAL Register of Controlled Trials (CENTRAL) < click here >
• KSR Evidence < click here >
  
  For each database list two aspects of the database's 'shape' that you had not known before. 

Strategy

docz.dz.

limit 1 to medline

limit 1 to "in data review"

limit 1 to in process

limit 1 to publisher

limit 1 to "pubmed not medline"

nb$.bk.

2 or 3 or 4 or 5 or 6 or 7

How to use Ovid’s Basic Search (NLP) to search quickly and efficiently across different databases, either individually or in combination, using words, phrases or sentences.

Background

When using biomedical databases for research, a common problem for beginners and advanced users alike, is how to find appropriate and relevant terms for the subjects being investigated. This could be because the user is unfamiliar with the subject or is working with the database from another language that differs from the language in which the subject terms are expressed. Or that the subject is new and that a consensus has not formed around key ideas and concepts and hence, have not yet found their way into the controlled vocabularies that are the basis of database thesauri, such as MeSH for Ovid MEDLINE and Emtree for Embase on Ovid.  

In such cases Ovid’s Basic Search can help. A natural language processing (NLP), relevancy ranking search engine, the Basic Search enables you to enter terms as simple expressions in any sequence. That is to say, there is no need to add Boolean operators or wildcard symbols or expressions. The entered terms are compared against those in a proprietary lexicon that Ovid has built to support the Basic Search and, following a statistical evaluation and ranking process, returns results on the basis of their calculated relevance to the terms you originally entered.

One of the many advantages of the Basic Search is that it executes on all the text fields of the database’s records. So, if the entry terms are found in the Subject Headings of the record or the Keywords, these will be highlighted. In this way you can see how the database is treating your original entry terms and subsequently make more precise searches using the database’s thesaurus or focused free term searching options. Being a field blind search, the Basic Search operates this way across all databases on Ovid.

Practice Suggestions

1. Enter the following sentence, complete ‘as is’, into the Basic Search on Ovid MEDLINE:
   do omega-3 fatty acids prevent cardiovascular disease?
   How many terms in the sentence have been flagged as MeSH (Tree) terms?
2. Limit the above search in point #1 firstly to Five Stars and then secondly, to publication years 2020 – Current. What ‘type’ of searches are these two latter ones: Basic or Advanced?
3. Run the three line search from point #2 above in Embase on Ovid or in any another database your institution has subscribed to. Have you had to change the search in any way for it to run successfully?

Strategy

adolescents adhd ritalin adverse effects

limit 1 to five stars

limit 2 to yr="2020 - Current"

How to use the commonly occurring database fields, Title (TI) and Abstract (AB), to search across different databases using words as well as phrases.

Background

Ovid MEDLINE, Embase on Ovid and more specialist resources like APA PsycInfo, are often described collectively as bibliographic databases. Or, even more specifically, as abstracting and indexing (A&I) databases. This description refers to a common feature they all share, namely that the record in the database is not the full-text equivalent of the original publication but a reflection of it. A reflection composed of specific units of information, called database fields whose own content or values have been gleaned from the original document and mapped to the database record. This process of converting the information from an original publication into a database record is carried out by indexers. The highly trained and qualified indexers at the National Library of Medicine (NLM) carry out this task for PubMed.

Generally speaking, original documents up for inclusion in the database, can be represented by their original title. The majority of these original documents, particularly those from scientific journals, will also have an abstract associated with them. These two pieces of information, taken over by the indexers ‘as is’, constitute the informational foundation of any database record. As such, rendered as the database fields, Title (TI) and Abstract (AB), either alone or in combination, they provide a sure and reliable way of retrieving information from any bibliographic database. Some of which, e.g.  Ovid MEDLINE and Embase on Ovid, are composed of tens of millions of records.

The recommended search mode for a Title (TI) and/or Abstract (AB) based search, either alone or in combination, is Ovid’s Advanced Search. Whereas in the previous Focused Search, the search terms adolescents adhd ritalin adverse effects were entered into the Basic Search search mode altogether in one line, the Advanced search can take and search for each term individually (see the search example, [Version 1: Terms as given], lines #1 to #4). The individual search lines can then be combined to achieve a result set that contains all of them (#5).

In this Focused Search the first iteration i.e. [Version 1: Terms as given] operates on the terms exactly as stated. So, for instance, the search engine only finds the term adolescent in its plural form. The singular version is not captured. Similarly the medication ritalin is only captured via its representation in the form of its brand name. The generic name of the medication, namely ‘methylphenidate’ is not captured. In such cases the term expressions can be enhanced using truncation and the addition of synonyms using the OR operator. See the search example, [Version 2: Terms enhanced], lines #6 to #10. For truncation Ovid employs the characters ‘*’ or ‘$’. Also known as ‘wildcards’, these can be used to search for ending variations of a word. See the Focused Search Targeted Searching using Term Variants (Wildcards) – All Databases for more detailed coverage of wildcards.

Practice Suggestions

1. Line #3 of the Focused Search retrieves a number of results for ritalin.ti,ab. As an alternative, run a truncated version of the search expression, i.e.  ritalin*.ti,ab. Drug trade names do not usually have a plural form, so what were you expecting? What did you find?
2. In Ovid it is possible to set the number of letters (n) that should follow the truncated search term prefix. Run the search expression  ritalin*1.ti,ab. To find ‘ritalin’ plus ‘ritalin plus 1’ additional character. Are the additional results relevant? 
3. Although the NOT operator can only be used via the command line, it is a very useful means of separating out sets of results. Use the NOT operator to isolate the additional results obtained from the previous search. What do the isolated results have in common?

Strategy

adolescents.ti,ab. [Version 1: Terms as given]

adhd.ti,ab.

ritalin.ti,ab.

adverse effects.ti,ab.

1 and 2 and 3 and 4

(adolescent$ or young adult$).ti,ab. [Version 2: Terms enhanced]

(adhd or Attention Deficit Hyperactivity Disorder).ti,ab.

(ritalin or methylphenidate$).ti,ab.

(adverse effect$ or adverse event$ or untoward effect$).ti,ab.

6 and 7 and 8 and 9

How to use the operators OR, AND, NOT, ADJ, ADJn and FREQ to include term variants and build search queries systematically.

Background

Overview

The Ovid platform provides a comprehensive selection of features and functions to help build robust search strategies that are able to cope with the complexities of both language and document composition. First and foremost among these features and functions are the so-called ‘operators’. Essentially, these are commands that instruct the search engine to combine search terms in a certain way. These commands, used individually but more usually in their combination, will enable you to carry out targeted searching. The operators available on Ovid are OR, AND, NOT, ADJ, ADJn and FREQ. An overview is given in the graphic below. Fuller details are provided in the Ovid Online Help as well as the Database Field Guide for the individual database you are searching in.

A note on the NOT Operator (See line #7):
When constructing searches using thesaurus terms in combination with free text terms, caution is advised with the NOT operator, as using it may run the risk of unwittingly excluding relevant documents. However, this operator is very effective for isolating document sets. 

A note on the ADJ and ADJn Operators (See line #4):
There are two variations of the Ovid proximity operator, ADJ and ADJn. The first, ADJ, carries out a regular phrase search finding the terms together in the order in which they have been entered. By contrast, the second variant, ADJn where ‘n’ is a number, carries out a search for the adjacent terms separated by n-1 words apart, the terms occurring in any order.

A note on the FREQ Operator (See line #12):
When used in Ovid, the FREQ or frequency operator shown in [Example 3], takes the form ‘x.ab./FREQ=n’ where ‘x’ represents a search term, ‘.ab’ the field in which the search should be conducted, here the Abstract  (AB) field, ‘freq’, the Ovid command for this function and ‘n’ the number of occurrences of term x being sought after. This operator can be used to great effect in full-text databases, such as the Cochrane Database of Systematic Reviews or YourJournals@Ovid. It can also be used meaningfully in text-rich fields such as Abstract (AB). In this Focused Search example, the terms being search for, i.e. truncated forms of the terms ‘migraine’ and ‘acupuncture therapy’ will return documents where these two ideas, occur together, at least 3 times each in the abstract field. The implication being that the returned documents are on point, are useful in their own right but can also be examined further to see how their subject headings and keywords treat the subject matter.

The 12 search expressions listed in this Focused Search also run on other bibliographic databases, for example, Embase on Ovid. Use the Change option on the Ovid platform to bring up the All Resources menu and select the database or the databases in combination, across which you want to search. 

Lastly, note too, the user created annotations, e.g. [Example 1]. These can be added to search lines when placed between block brackets [ ]. The annotations can also be added to, amended, or deleted using the Edit option available via the search screen under Actions / More / Edit.

Practice Suggestions

1. Using the ADJ operator renders line #4 more succinct. How would further increasing the number ‘n’ impact your results? How can you test that the ADJn-based search expression is indeed delivering the search term words in the phrase combinations you expect?
2. In [Example 2], in specifically search line #10, the US spelling of ‘randomized’ as well as the British spelling, ‘randomised’ are used. How could you use the ADJ operator to reduce the number of terms in the search expression, yet yield the same number of results for the search?
3. The search in line #12 yields only three results. Name three ways with which you could derive additional benefits from using this search expression. 

Strategy

(adolescents or young adults or teenagers).ti,ab. [Example 1]

(adhd or Attention Deficit Hyperactivity Disorder).ti,ab.

(ritalin or concerta or daytrana or equasym or methylphenidate).ti,ab.

(adverse events or ((adverse or untoward or side) adj3 effects)).ti,ab.

1 and 2 and 3 and 4

(infant or infants or child or children or preschool or pre school).ti,ab.

5 not 6

(migraine or migraines or sick headache or sick headaches or status migrainosus).ti,ab,kf. [Example 2]

(acupuncture therapy or acupuncture treatment or acupuncture analgesia or ear acupuncture or electroacupuncture or meridians or acupuncture points or moxibustion).ti,ab,kf.

(randomized controlled trial or randomized controlled trials or randomised controlled trial or randomised controlled trials).ti,ab,kf.

8 and 9 and 10

migraine$.ab. /freq=3 and acupuncture therap$.ab. /freq=3 [Example 3]      

How to use Ovid’s character replacement options, so-called ‘wildcards’, to include singular and plural versions of search terms as well as other possible variations.

Background

The Ovid platform provides a comprehensive selection of features and functions to help build robust search strategies that are able to cope with the complexities of both language and document composition. For instance, spelling variations are a challenge when formulating search expressions. Not only are there regional spelling differences, e.g. British versus American spelling, but also very commonly, singular and plural forms of words.

Ovid provides a comprehensive selection of so-called ‘wildcards’ to accommodate these differences. Generally speaking, wildcards are symbols that can be used as character replacement holders. Some wildcard characters can be entered with numbers to indicate the number of characters for which a place or places should be held. An overview is given in the graphic below.

Fuller details are provided in the Ovid Online Help as well as the Database Field Guide for the individual database you are searching in.

A note on searching for text strings “n” (See line #12):
Although Ovid performs phrase searching by default, quotation marks “ ” , can be used to require Ovid to search for the expression as a literal string. This is particularly helpful when the string includes special characters, such as a forward slash (/) or reserved words, such as the word ‘use’. On the Ovid platform the word ‘use’ is a reserved word in that it is interpreted as a command. In combination with a database’s abbreviation, e.g. medall for Ovid MEDLINE ALL, Ovid understands this expression as a command, i.e. use medall to change from the resource you are in, to the database, Ovid MEDLINE ALL. This being the case, the search substance use.ti,ab. would need to be entered as ”substance use”.ti,ab.

Practice Suggestions

1. Drug trade names, like ‘Ritalin’ are usually clear cut terms and do not warrant truncation with wildcard characters. That said, would there be any benefit in truncating ritalin in line #3 even in a limited way, e.g. using the search expression  ritalin*1.ti,ab. for example. How would you establish the usefulness or even a possible need for this.
2. Drawing upon the example in line #6, run the searches child$.ti,ab. and child$3.ti,ab., the latter in a separate line. Use the NOT operator to establish the difference in the numbers of results between them. What terms have you obtained with child$.ti,ab. that were excluded by child$3.ti,ab.?
3. Previous test searches using the ADJ operator for line #10 established that it could be rendered efficiently as ((randomized or randomised) adj (controlled trial or controlled trials)).ti,ab,kf.  With specific wildcards we can now further reduce this to (randomi#ed controlled trial$).ti,ab,kf.. On the face of it, these two expressions should return the same number of results. Do they? Were there to be a difference, how could you explain it?

Strategy

(adolescent$ or young adult$ or teenager$).ti,ab. [Example 1]

(adhd or Attention Deficit Hyperactivity Disorder).ti,ab.

(ritalin or concerta or daytrana or equasym or methylphenidate).ti,ab.

(adverse event$ or ((adverse or untoward or side) adj3 effect$)).ti,ab.

1 and 2 and 3 and 4

(infant$ or child$3 or preschool or pre school).ti,ab.

5 not 6

(migraine$ or sick headache$ or status migrainosus).ti,ab,kf. [Example 2]

(acupuncture therap$ or acupuncture treatment$ or acupuncture analgesia or ear acupuncture or electroacupuncture or meridian$ or acupuncture point$ or moxibustion).ti,ab,kf.

(randomi#ed controlled trial$).ti,ab,kf.

8 and 9 and 10

("wom#n with migraine" or "m#n with migraine").ti,ab. [Example 3]