Q. Why should I search PubMed using a search string that includes phrase searching (quotation marks/inverted commas " ") as well as a search string that does not?

Identifying phrases instead of separate keywords in your search string will help focus your search to find relevant results. The only problem is that PubMed has its own phrase index and your phrase may or may not be included in this index.

So to make your search as systematic as possible, we suggest that you use TWO Basic searches - one with phrases and one without, e.g.,

1. ("social media" OR "social networking" OR "digital support groups" OR "online health communities") AND ("high blood pressure" OR hypertension) AND (self-management OR self-care OR self-regulation OR self-monitoring OR "self care" OR "self management" or "self regulation" OR "self monitoring")
2. (social media OR social networking OR digital support groups OR online health communities) AND (high blood pressure OR hypertension AND (self-management OR self-care OR self-regulation OR self-monitoring OR self care OR self management or self regulation OR self monitoring)

Searching in this manner will help increase your success at finding the articles/evidence that you need.