Table 2 Overlap analysis

Number of columns (number of reviews)

c

47

Number of rows (number of index publications)

r

499

Number of included primary studies

(including double counting)

N

1206

Covered area

N/(rc)

5.14%

Corrected covered area

(N-r)/(rc-r)

3.08%

Interpretation of overlap

Slight overlap

Structural zeros

X

0

Corrected covered area

(adjusting by structural zeros)

(N-r)/(rc-r-X)

3.08%

N° of non-overlapped primary studies

In 1 SR

294

Number of overlapped primary studies

In 2 SRs

79

In 3 SRs

33

In 4 SRs

14

In 5 SRs

13

In 6 SRs

16

In 7 SRs

10

In 8 SRs

9

In 9 SRs

4

In 10 SRs

8

In 11 SRs

2

In 12 SRs

3

In 13 SRs

1

In 14 SRs

2

In 15 or more SRs

5