Systematic searching and chain searching are two strategies for information retrieval that you might use for instance for finding earlier research for a literature review. In systematic searching you go through a search process several times. Chain searching means that you start from already available sources in order to find more material.
When writing an essay or a dissertation you might need to dig deeply into the research in your subject area. For a comprehensive result you may make use of in-depth strategies for information searching. On this page we describe the search strategies systematic searching and chain searching.
In a systematic search you follow several different steps in a search process, which is then repeated until you judge that you have finished. Searching in such a structured manner enables you, for instance, to map previously published research in your subject field.
Searching for information is a process where different elements interact with each other. Follow these steps for a systematic search.
Start from your purpose and research question
Start from your purpose and your research question when searching. Your research question affects the search process – if it is too broad, too narrow, or unclear it might be difficult to find material.
You might need to modify your purpose and research question while you are searching for information. This is a natural part of the search process.
Select search terms
Before starting your search you need to consider which of the words in your research question are most important and carry most meaning. These keywords will form the basis for your search. Then find synonyms for your keywords to increase the number of search terms you can use.
In the majority of research areas you get better hits if you search in English. A research question like "How does the electoral system influence female representation in the UK House of Commons?" might for instance generate the following English search terms:
A list of subject terms (thesaurus) – an integral part of some databases – is another aid to finding good search terms. Lists of subject terms can help you
Carry out your search in relevant databases
Once you have established your search terms it is time to start searching. Select a few databases or search tools that are relevant to your subject.
The database list in the library search tool shows you which databases exist in a particular subject:
Your search will be more effective if you use various search strategies, such as
Sample search string: ("election system" OR "electoral system" OR "voting system") AND ("Great Britain" OR "United Kingdom" OR UK) AND representation AND (women* OR female*) AND "House of Commons"
Many databases and search tools also include filter functions which can make it easier for you to find relevant material.
Here you can find further reading and videos about basic search techniques:
Document your searches
Make notes of your searches in the course of the search:
This saves time for yourself, and you can also tell other people how you have carried out your searches.
If you do a literature review as your degree project you might be required to provide detailed documentation of your searches.
Examine the result of your search
Once you have carried out your search it is important to examine the result:
Take a closer look at your hits and see if you can identify new keywords. You might for instance look at the subject terms, abstract and full text of the hits.
Also remember to evaluate how credible the hits are. In many databases it is possible to single out hits from scholarly journals via filters such as "peer review". However, it is always up to you to assess whether a source is or is not scientific.
Save information about your sources for the reference list
When you have found good sources that you want to use in your work it can be a great help if you save the data for your reference list in a systematic manner.
To facilitate working with references you can use reference management software or functions available in databases to create ready-made references. When you save and create references in this way it is important always to check that all necessary information about the source is included and that the reference is correct in terms of the reference system you use.
Here you will find more information about references and reference management software:
Adjust and repeat until you are satisfied
Think about how you might adjust your search terms and your search to get hits that are as relevant as possible. Information searching is a process in which you have to repeat searches and finetune them based on the hits you get from each search. Then carry out new searches incorporating new terms that you have generated during the process.
Often you also have to return to other steps within the search process:
Continue adjusting your searches until you judge that you have carried out a sufficiently extensive mapping of the research within your subject field.
If you need to know more about systematic searching we recommend two guides from the Karolinska Institute University Library (KIB). One is aimed at students and the other at researchers and doctoral students.
If you have already found, or been recommended, certain sources you might start with these in order to find other relevant literature. This search strategy is often called chain searching as you can regard the different sources as links in a chain. By following references from one relevant source to others you follow a kind of chain that leads you to more material.
Once you have identified your starting points there are several different ways for you to progress in your chain searching.
Use reference lists to find new sources
Going through reference lists in sources that you have already found could be a good way of finding new and interesting sources.
Search based on citations to find important sources
Check books and articles recommended by your supervisor or experts within your subject field. Have they been cited in other sources?
Large databases such as Google Scholar, Scopus, Web of Science and certain subject specific databases have good tools for calculating the number of citations a publication has generated.
Find new sources in review articles
A review article is a summary of a certain research area produced by one or several researchers. The review article also lists key sources and researchers.
Try finding up-to-date review articles so as to include the latest research within your subject. Large databases such as Scopus, Web of Science and PubMed include good tools for filtering out review articles.
Pay attention to references while reading
When you start reading to familiarise yourself with your subject, it is a good idea to pay attention to whether certain researchers and sources frequently reoccur in the literature. If a source is cited in several other sources this could be a sign that it is important within your subject area.
Library search tool
Search broadly for articles, dissertations, reports and books in the library search tool.
Do in-depth searches on your subject using the library's databases.
Basic course in information search
In our open online course, you will learn how to find scientific articles and other material for your studies.
Basic search techniques
Use different search techniques to perform better searches in the library search tool and other databases.
Scholarly articles and other publications
Learn more about scholarly articles and the differences between various types of scholarly publications.
Evaluation of sources
Be critical of your sources - ask questions to assess the credibility of scientific publications.
Do you feel lost among databases and scholarly publications? Visit our drop-in sessions or make an appointment for a tutorial and we will help you. You can also submit short questions via chat or the contact form or ask the staff at the information desk.
Drop-in and lectures for students
Visit our drop-in sessions and ask your questions about information searching and evaluation of sources.
Schedule a tutoring appointment
Make an appointment for personal tutoring when you need more help with information searching.
Contact the library
Do you have a quick question about information searching? Please use our contact form or chat feature.