Google Scholar as replacement for systematic literature searches: good relative recall and precision are not enough

Table 1 Precision and recall of the Google Scholar searches for studies included in fourteen Cochrane

Review on	References included^*	References found	Hits	Precision [%]	Recall [%]
Antidepressants versus placebo for depression in primary care [21]	14	11	17,400	0.06	78.6
Artemisinin-based combination therapy for treating uncomplicated malaria [22]	49	49	5,320	0.92	100
Brief interventions for heavy alcohol users admitted to general hospital wards [23]	14	14	18,000	0.08	100
Combined DTP-HBV-HIB vaccine versus separately administered DTP-HBV and HIB vaccines … [24]	20	20	4,320	0.46	100
Erythropoietin or Darbepoetin for patients with cancer - meta-analysis based on individual patient data [25]	48	41	36,500	0.11	85.4
Green tea (Camellia sinensis) for the prevention of cancer [26]	51	48	17,900	0.29	94.1
Incentive spirometry for prevention of postoperative pulmonary complications in upper abdominal surgery [27]	11	11	13,400	0.08	100
Interventions to prevent occupational noise-induced hearing loss [28]	24	24	19,500	0.12	100
Non-pharmacological interventions for assisting the induction of anaesthesia in children [29]	17	16	29,300	0.05	94.1
Oral iron supplements for children in malaria-endemic areas [30]	70	62	67,800	0.09	88.6
Pharmacotherapy for anxiety disorders in children and adolescents [31]	22	21	17,700	0.12	95.5
Single dose oral flurbiprofen for acute postoperative pain in adults [32]	11	11	7,950	0.14	100
The effects of antimicrobial therapy on bacterial vaginosis in non-pregnant women [33]	24	24	18,700	0.13	100
Therapeutic interventions for symptomatic treatment in Huntington’s disease [34]	21	16	17,400	0.10	76.2
Total	396	368	291,190	0.13	92.9

We used the Cochrane Database of Systematic Reviews issue 3/ 2013 (Gehanno et al. used Issue 3/2009 [9]).
^*: “References included“ is the number of single references of included studies with one major reference per study as retrieved from the Cochrane reviews.

ISSN: 1471-2288