After talking about setting a precise question (PICO), let’s look at the search results!
We know that sometimes we see a situation where the results give us two thousand papers. That’s definitely overwhelming, making you doubt whether your keywords weren’t good enough, and so on. But, did you think you could just clap your hands in satisfaction when there are only 5 results!? (Well, obviously yes when you’re rushing to finish a report xD)
Let’s look at what to do when there are too many or too few results!
Search methods overview
Let’s first understand what search methods are out there, before we talk about how to handle too many or too few results.
- Free text: Typing in search terms at will. You have to rely on background knowledge to type out all the synonyms.
- MeSH term: You should use this when there are many synonyms. These are tags the database assigns to each article (there’s a group of people working hard behind the scenes to categorize them!). They cover almost all synonyms and save you a massive amount of time.
- Title search: Restricts the search to only titles containing the term. Used when there are only one or two clear names; it can increase specificity.
- Boolean logic: Strings multiple terms together flexibly. It includes AND, OR, and NOT, creating endless possibilities xD
- Filter: Almost all mainstream databases have this, located in the sidebar on the left. It lets you set the study type, publication date, study population, etc.
Too many results, what should you do?
Seeing a thousand or two articles pop up in front of you, you immediately throw your hands up in surrender. How can you finish reading them all, and how can you find the most suitable one?
At this point, we need to narrow down the search scope. The methods we can use are:
- Use Title search instead of MeSH: For example, when searching for painkillers, don’t use the broad MeSH category of NSAIDs. Instead, use Title search to look for the specific drug you’re interested in, like indomethacin.
- Add Filter restrictions: You can restrict it to only look at Guidelines and Systematic reviews with the highest level of evidence, or only look at articles published in the last five years, etc.
- Leverage NOT logic: Sometimes a lot of off-target articles of the same type show up. You can use NOT to remove unwanted results, and you can pair it with MeSH to broadly exclude specific results.
- Echoing the “prognostic studies” from the previous post, since we don’t want any treatments, we can use NOT to exclude those treatments.
Too few results, is that okay?
If all the articles perfectly match our clinical question, we actually can’t get too happy about it…
A search result that’s too accurate means we might not have found some articles (it’s the concept of the trade-off between sensitivity and specificity). At this point, we should actually think hard about how to loosen the criteria.
- Use MeSH term: Click into one of the articles, see what keywords it was tagged with, and use them directly for your search.
- Use Similar article: Find the one that matches best, and let the database itself suggest articles it thinks are similar.
- Switch to Free text: MeSH updates actually take 3 months, so studies that are too new won’t be included in it. You can try using free text to find them.
- Loosen all other criteria: don’t be too strict on the study type, doesn’t have to be the newest, any drug in the same class is fine, etc.
To sum it up
We have a lot of search methods, and combining them is all about distinguishing what increases sensitivity and what increases specificity. Hope this helps everyone find the articles they want!
- Find more articles (increase sensitivity): MeSH term, similar article, OR
- Find fewer articles (increase specificity): Title search, filter, NOT