I want to search for papers with this criteria : the title contains preeclampsia OR the title contains toxemia and the text contains pregnan*.

I used this:

intitle:preeclampsia  OR (intitle:toxemia AND intext:pregnan*)  489 hits

But google scholar didn't understand the parenthesis and gave the same results as this:

intitle:preeclampsia  OR intitle:toxemia AND intext:pregnan*   489 hits

What's wrong?

closed as off-topic by jakebeal, vonbrand, scaaahu, David Richerby, Massimo Ortolano Feb 6 '16 at 12:47

  • This question does not appear to be about academia within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

  • What's wrong is that you aren't just doing two searches, which could achieve the same effect. Seriously, though, Google tinkers with their algorithms all the time, and guesses what they think you meant, which can play merry hell with precision searching. If you want precision searching, use a different search engine like PubMed. – jakebeal Feb 5 '16 at 19:18
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    I'm voting to close this question as off-topic because it is about the (often changed) specifics of Google search engine execution. – jakebeal Feb 5 '16 at 19:19
  • Why do you think Google Scholar didn't understand the parenthesis? The results you've got are more likely to be the result of AND having a higher priority than OR. – EnergyNumbers Feb 5 '16 at 19:48
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    @jakebeal Why do you think it's a 'specifics of Google search engine execution.'? I though it's a mistake in my search. – Elmahy Feb 5 '16 at 20:00
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    @ahmedmar Because I've watched Google responses change over the years as the engine has been improved and updated, with some of these updates making it harder to search for some things even as it becomes easier for others, and it does not appear to be a stable platform that one can count on to maintain consistent behavior over time. – jakebeal Feb 5 '16 at 20:22

As you correctly recognized, Google Scholar doesn't understand parentheses. I don't think there is a solution other than making two separate searches and considering the results of both. If you wish to get a literature overview, that should be sufficient.

If you wish to count the number of hits, you may want to make a third search for intitle:preeclampsia AND intitle:toxemia AND intext:pregnan* and use the inclusion-exclusion formula: |A or B| = |A| + |B| - |A and B|. (Warning: the number of results is just approximated in Google searches, and this method may return numbers that are way off).

If you wish to do something else, just tell us in the question next time. :)

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