## 3.1 Search methods

What is a search method ?
A search method ensures that you can find the information you need to answer your research question in an efficient and effective manner. The best search method to use depends on the subject of your research and the desired outcome.
In this section, we explain various search methods so that you know which search method or combination of search methods to use.

Pearl growing

Pearl growing can be used to collect more search terms. Perform a search and see if there are any other useful search terms in the search results. Then continue searching with the newly found terms.

Pearl growing example

For example, you start by searching for obesity in START and see if the results contain good, useful terms or keywords. In the image below you can see all kinds of terms under 'subjects' that you can use to continue your search.

Snowball method

Many publications include a list of references (or bibliography) at the back. This provides an overview of the literature used by the author. You can use this list to find more related and interesting sources. A disadvantage of this method is that it may not yield the most recent information. The snowball method takes you back in time.

Citation method

The citation method works in exactly the opposite way. When you find a relevant article, you look at which other sources refer to this article. This allows you to find more recent literature on the topic. The citation method allows you to search forward in time.

Example of the citation method

In the example bellow you will see 'Cited by' in a Google Scholar search. If you click on this you will find (more recent) articles by authors who have used the article.

Building blocks method

With the building blocks method, you divide your search query into different topics. You collect search terms for each topic in your query. Combine search terms from all topics into a single search query (search string).

How best to combine search terms will be explained in the next section.

Example of the building blocks method

You have collected the search terms below because you are looking for literature on 'measures taken by school canteens to combat obesity'. If you only search for obesity, you are likely to get a lot of search results, most of which will not be relevant. If you add search terms for the other topics, your search will be more specific. For example: obesity policy school canteens. You will get fewer, but more relevant results. You can improve this even further by combining your search terms with Boolean operators.

Topics | Search terms
Obesity | overweight, obesity, healthy weight
Canteens (universities of applied sciences) | school canteens, canteens, schools, caterers, university of applied sciences, students
Measures | measures, prevention, policy, guidelines, food choices, food supply

(overweight OR obesity) AND ("school canteens" OR canteens OR schools) AND (measures OR prevention OR policy OR guidelines)

With the above search string, one of the words from each topic must appear in the search results. So you could find an article with the words: obesity + canteens + prevention. Build up a comprehensive search string by continuously testing which search terms work. You do this by continuously adding or removing words. Continue to do this until you have the right search results.