Aims/Objectives
High quality, structured searches need to be accurate and comprehensive. Before finalising your structured search, make sure to review your search strategy following the checklist and top tips available in this guide.
If you are not sure what the checklist is asking you to look for/review in your search, explore each of the Top Tips for more detail. There is also a quiz for each Tip for you to check your understanding.
Checklist for reviewing your search strategy
Make sure to use the checklist to review your search strategy. If you need more information about the top tips, read the sections below on each tip and take the quizzes to test your knowledge.
1. Check you have used the correct Boolean operators for what you want your search to do.
The main Boolean operators we use are AND and OR.
AND
AND will always give you less results. Use it when you mean that all of the words you have connected with AND must come back in your search results. AND can help searches to be more specific.
Be careful, if you connect too may terms with AND you will end up with no results.
OR
OR will always give you more results. Use it to connect synonyms together (alternative keywords) for the terms you need to come back in your search.
There might be lots of ways to say your keywords or there may only be one way, but if you haven’t used OR in your search at all, it doesn’t sound like you have been sensitive enough with your search strategy.
If you are struggling to come up with alternative keywords (synonyms), have a look at the planning page on the structured searching guide (scroll down to the section Keywords and Synonyms).
When using OR it is important to check that the keywords you have combined with OR are genuinely appropriate to your search results. Using OR incorrectly could bring back lots of irrelevant results.
AND and OR
To get the best results from your search you need to identify as many relevant synonyms for each concept as you can, and combine those with OR, before connecting those broadened out terms with AND.
Sometimes there can be confusion with a search when using the PI/ECO formula and there is more than one part to a particular aspect you are searching for. For example, you might be searching for information on a population group who are teenagers who smoke or adults who have breast cancer.
A common searching error is to combine all of these terms with OR (because they are all part of the Population). For example:
- Teenager OR smoking
- Adult OR breast cancer
But this is incorrect. You would get lots of irrelevant results, as the articles might only contain one part of the population group you are interested in.
It would be much better to separate these terms, think of any appropriate synonyms, and then re-connect them with AND. For example:
- (Teenager OR adolescent) AND (Smoking OR Cigarette)
- (Adult OR Middle Aged) AND (Breast cancer OR breast malignancy)
There is more information about using Boolean operators here: https://libguides.tees.ac.uk/cinahl/planning
Test your knowledge about reviewing the Boolean operators used in your search strategy by taking the short quiz below.
2. Look at the keywords you have used in your search.
Make sure you haven’t repeated any terms unnecessarily.
Sometimes repeated terms are seen in search strategies as there has been some difficulty coming up with useful synonyms.
If you are struggling to come up with alternative keywords (synonyms), have a look at the planning page on the structured searching guide (scroll down to the section Keywords and Synonyms).
However, repeated terms won’t make your search any better and won’t bring back additional results.
For example:
- A search for diabetes will find anything to do with diabetes, so searching for diabetes OR type 2 diabetes, won’t find any additional results.
- A search for diet will find anything to do with diet, so searching for diet OR healthy diet won’t bring back results you haven’t already got.
If you have decided you want to make your search more focussed – looking only at type 2 diabetes, then you would need to replace the term diabetes with type 2 diabetes completely, rather than adding it on as an option with OR.
Avoid using terms which could lead to bias.
When researching, you may want to know if an intervention has been effective – i.e. has it reduced breathlessness, reduced pain or improved survival rates.
For example:
- If you are researching whether bystander CPR has improved the survival rates of cardiac arrest patients out of hospital it would be better from a searching point of view to include the broader word survival (and its appropriate synonyms) as the outcome, rather than only looking at the results which show improved survival rates (what if some research shows it hasn’t improved them?).
- If you want to investigate if complementary therapies are effective at reducing pain during labour, it would be better from a searching point of view to include the broader word pain (and its appropriate synonyms) as the outcome, rather than only looking at the results which show that it had reduced pain (what if some research shows it hasn’t reduced pain or hasn’t made any difference?).
Test your knowledge about reviewing the keywords used in your search strategy by taking the short quiz below.
3. Search for one keyword or phrase at a time.
We recommend searching for one keyword or phrase at a time in databases like CINAHL, Medline and Embase.
This way you can check the results you get back for each keyword or phrase you search.
If you have made a spelling mistake or a typing error (the databases don’t auto correct) you can see it quickly, as you will only get a couple of results or none at all.
On the flip side, by searching for one keyword or phrase at a time, you can also see if you have searched for terms which bring back too many results. This can be quite common if you have a broad intervention, issue or outcome.
Using the words intervention, issue or outcome in a search will bring back lots of results. If you have too many to go through, it might be worth thinking of which specific interventions, issues or outcomes you want to look at.
Test your knowledge about searching for one keyword or phrase at a time by taking the short quiz below.
4. Avoid using unnecessary limits/filters.
The filters or limits you see in the databases can be useful.
The most common filters people use are to limit by:
- date/time period
- age
- language
However, be wary about using too many other limits and filters as they could limit your search too much.
Sometimes the limits might not be as helpful as you think. For example:
- The geography limit could mean the place the journal is published rather than the location that the study took place.
- The full text limit won’t show the results which we have access to in other databases or outside of our holdings (and the Inter Library Loans service may be able to give you access to resources beyond what we subscribe to.)
The tags that some databases use for their filters (e.g., a study design filter such as RCT) may not have been added onto the most recent records in the database, so you may miss some newer results.
To limit the results to a specific study design, you could instead use an additional string of keywords:
For example:
- RCT* OR Random* Control* OR Placebo OR Clinical* Trial* OR Clinical Stud* OR Random* assign*
- Qualitative OR Narrat* OR Phenomenolog* OR “Grounded theory” OR Ethnograph* OR “focus group*” OR interview*
For more information about using the advanced searching techniques shown in the search strings above, see the tip on using advanced searching techniques correctly
For more information about quantitative and qualitative research see the Research Methods guide.
Test your knowledge about using limits and filters by taking the short quiz below.
5. Use advanced searching techniques and make sure you know how the database works to ensure you are using them properly.
In the main health databases, there are a number of advanced searching techniques you can use to improve the thoroughness of your searches.
The main advanced searching techniques used are truncation and phrase searching.
Truncation should generally give you more results and phrase searching should reduce your results. If you notice that this is not happening, check the help screen on the database.
Not all databases support advanced searching techniques and the symbols used may vary.
In most databases the symbol for truncation is the asterisk * and the symbol for phrase searching is the double speech marks “”.
However, in the Ovid databases (Embase, Maternity & Infant Care and HMIC) the search automatically phrase searches and won’t recognise the double speech marks.
There is more information on how to search in a range of the health databases on the structured searching guide:
- In the EBSCO databases (CINAHL, Medline, Amed, APA PsycInfo, Sport Discus and Dentistry & Oral Sciences)
- In Embase, Maternity and Infant Care, Scopus and others
Truncation (*) is also known as “stemming”. You can use it to search for a term and variant spellings of that term, by substituting the letters at the end of the word for an asterisk (*). Your search then finds every word that begins with the letters you have entered.
For example,
- Asthma* will retrieve asthma and asthmatic.
- Diabet* will retrieve diabetic and diabetes.
You can use double speech marks ("") when you want to find an exact phrase, for example, "Vitamin C”. This will find only documents where those words appear next to each other and in the same order. Remember in the Ovid databases you won’t need to use the double speech marks.
You can also use truncation and phrase searching together. This can be useful when you want to use phrase searching but still pick up the various endings, including plurals.
- A search for “Daily li*” would keep your keywords together, in the same order, and as well as finding “daily life” it would also find “daily living”.
- A search for “Health care worker*” will find the phrase as well as enable you to find the plural health care workers.
For more information about the advanced searching techniques see the planning section of the structured searching guide (scroll down to Advanced Searching Techniques).
Test your knowledge - Use advanced searching techniques