Table 3 |
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Comparison of articles identified through Science Citation Index and PubMed searches until the end of 2003 |
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|
Search method(s) that identified article |
PubMed and Science Citation Index (n = 31) |
Science Citation Index only (n = 11) |
PubMed only (n = 8) |
|
|
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|
Mean (s.d.) |
1999 (6.4) |
1996 (7.9) |
1997 (9.9) |
|
Median (range) |
2002 (1969–2003) |
2001 (1982–2003) |
2001 (1973–2002) |
|
Impact factor |
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|
Mean (s.d.)* |
4.2 (2.8) |
9.5 (9.8) |
3.9 (2.6) |
|
Median (range) |
3.2 (1.1–10.5) |
3.8 (2.0–31.7) |
2.8 (1.3–7.6) |
|
Study Type |
8 aetiologic 23 prognostic |
3 aetiologic 8 prognostic |
2 aetiologic 6 prognostic |
|
Classification of outcome** |
25 positive 6 null |
5 positive 6 null |
6 positive 2 null |
|
Sample size: aetiologic studies |
|||
|
Mean (s.d.) |
4502 (3331) |
5758 (4397) |
1101 (1089) |
|
Median (range) |
3269 (76–9758) |
7217 (817–9239) |
1101 (332–1870) |
|
Sample size: prognostic studies |
|||
|
Mean (s.d.) |
525 (626) |
832 (925) |
399 (441) |
|
Median (range) |
344 (30–2885) |
552 (58–2320) |
288 (66–1250) |
|
|
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* Four articles were published in journals with no impact factor (1 both methods, 1 Science Citation Index only, 2 PubMed only). **Statistically significant result at the p < 0.05 level. |
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|
Kuper et al. BMC Medical Research Methodology 2006 6:4 doi:10.1186/1471-2288-6-4 |
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