Building your search string

Conducting a good search requires a bit more than just putting single search terms in a search bar. In order to retrieve specific and targeted information about your topic, you need to logically combine search terms with each other. To do that, you use Boolean operators:

• AND: if you are looking for references in which both search terms appear;
• OR: if you are looking for references containing at least one of the search terms;
• NOT: if you are looking for references in which a particular search term does not occur.

Note: Be careful when using NOT; it may exclude relevant articles by inadvertently (false negatives). A suggestion here is: run the search with and without the NOT, and see the difference by comparing the results in your Search History: how many results are omitted? Are the results that are omitted relevant to your search or not? Based on this, you can decide whether or not the NOT is a useful addition to your search string.

How to build a search string:

• collect search terms and keywords by subtopic;
• combine them with OR;
• place the keywords between parentheses;
• put an AND between the subtopics

Generic example: (... OR ... OR ... OR ... OR ...) AND (... OR ... OR ... OR ...) AND (... OR ... OR ... OR ... OR ...)

With this, you have created a basic search string that you can use for multiple databases. For some databases, you can fine-tune the search string by adding thesaurus terms and/or search fields (see below).

Several techniques exist for fine-tuning your search string. Note that databases often have their own 'rules'. It is advisable to check per database which 'rules' apply to the syntax of your query. These can be found in the HELP or FAQ section of the database in question.

Exact word combination
If you only want to find search results that contain the search terms in exactly that order, place your search terms inside double quotation marks ("....."), e.g. "Attention Deficit Hyperactivity Disorder." 

Pro tip: an exact word combination is actually a strict version of the Boolean AND operator, where the search terms must also occur in that particular order. Therefore, the order of the search terms is not arbitrary, but set by you. 

Truncation

Truncation is a technique that can be used to expand your search; the end of a search term is replaced by a truncation mark, also known as a wildcard. Doing so allows you to efficiently find word variants and thus expand your search. For example:

• child* = child, children, childhood, childhood, child-friendly, childs, child-like
• industr* = industry, industries, industrial
• genetic* = genetic, genetics

Truncation symbols may vary by database, but frequently used symbols include *, !, ? or #.

Wildcards:

A wildcard is a symbol that replaces a letter of a word. This is especially useful when a word can be spelled several ways (but mean the same thing), such as in a British variant as an American variant. For example

• wom!n = woman, women
• colo?r = color, color
• latin?= latina, latinx, latine, latino, latines

Search fields
When you enter your basic search string into the search bar, your search terms will generally be checked to see if they appear anywhere in the text of the article. This can potentially create a lot of noise. Limiting your search to a to specific search fields will make it more focused. Advanced Search allows you to search only certain fields, e.g. title and/or abstract, keywords, or subject.

For example, "language development disorder"[abstract] AND "primary school"[abstract] AND "teaching materials"[abstract].

Note that each database has its own configuration and search fields, so always tailor your search to the database!