Google Scholar

Appraisal of: Wright K, Golder S, Rodriguez-Lopez R. Citation searching: a systematic review case study of multiple risk behaviour interventions. BMC Med Res Methodol. 2014; 14:73.

Short description: 

Study about the effectiveness of using the citation sources Google Scholar, Scopus, Web of Science and OVIDSP MEDLINE to identify records for inclusion in a systematic review about multiple risk behaviour interventions.

40 included studies were used identified by traditional database searches from one systematic review. Each of the included studies was searched for in the four citation sources to retrieve the details of all papers that have cited these studies.

The highest number of citations was retrieved from Google Scholar (1680), followed by Scopus (1173), then Web of Science (1095) and lastly OVIDSP (213). To retrieve all the records identified by the citation tracking searching all four resources was required. Google Scholar identified the highest number of unique citations. The citation tracking identified 9 studies that met the review’s inclusion criteria (recall 22,5%).

Conclusion: Citation searching as a supplementary search method for systematic reviews may not be the best use of valuable time and resources.

Limitations stated by the author(s): 

In terms of searching, the scoping review had very broad coverage. Its aim was to identify any intervention promoting change in at least two risk behaviours and the search strategy incorporated terms for all of these (smoking, alcohol misuse, physical inactivity, unhealthy diet, illicit drug use, sexual risk behaviour, lack of seat belt use, lack of motorcycle/bicycle helmet use, lack of sunscreen use, gambling, poor oral hygiene and drink driving) in various set combinations. The resulting complexity will almost certainly have had an impact upon the overall performance of the database search strategies. As with any case study, there is uncertainty about how far the results of this study can be generalised, especially to other reviews with a more restrictive focus.

Limitations stated by the reviewer(s): 
No additional limitations were detected by the reviewers.
Study Type: 
Single study

Appraisal of: Linder SK, Kamath GR, Pratt GF, Saraykar SS, Volk RJ. Citation searches are more sensitive than keyword searches to identify studies using specific measurement instruments. J Clin Epidemiol. 2015; 68(4):412-417.

Short description: 

The aim of the study was to compare the effectiveness of two search methods in identifying studies that used the Control Preferences Scale (CPS), a health care decision-making instrument.

The literature was searched using two methods: (1) keyword searching using variations of ‘‘Control Preferences Scale’’ and (2) cited reference searching using two seminal CPS publications. Three bibliographic databases [PubMed, Scopus, and Web of Science (WOS)] and one full-text database (Google Scholar) were searched.

Keyword searches in bibliographic databases yielded high average precision (90%) but low average sensitivity (16%). PubMed was the most precise, followed closely by Scopus and WOS. The Google Scholar keyword search had low precision (54%) but provided the highest sensitivity (70%). Cited reference searches in all databases yielded moderate sensitivity (GS: 54%, WoS: 45%, Scopus 52%), but precision ranged from 35% to 75% with Scopus being the most precise.

When trying to identify many articles using a particular instrument, cited reference searching in Scopus or WOS is preferable to keyword searching in these resources or in PubMed/MEDLINE. However, in Google Scholar, a full-text database, a keyword search for CPS found more studies than the cited reference searches and precision was slightly higher.

If the goal is to identify a few studies that use a specific instrument, keyword searches of a bibliographic database may be the most efficient. When it is important to conduct a comprehensive search to maximize the number of studies found, both cited reference and keyword searches should be conducted in more than one database. 

Limitations stated by the author(s): 

“Our case study has limitations. The search results for the CPS may not be applicable to similar searches for other instruments. Other instruments may be more or less likely to be referred to in database records or article references. Results may also vary for a different information retrieval goal such as searching for a specific outcome reported in an instrument. In addition, our keyword search strategy was limited to the name of the instrument (and a variation of the named ‘‘preferences’’ instead of ‘‘preference’’) so that an identical search could be performed in each database. A more complex strategy that uses terms related to the instrument (ie, role preferences, patient involvement) could provide different results.”

Limitations stated by the reviewer(s): 
Authors did not state the recall in Google scholar for both articles used for citation tracking. It seems to be necessary to have initial article that introduced the instrument and the validation study.
Study Type: 
Single study
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