Table 1 Classification of quality indicators of studies included in the review

Bagley 1997 [9]

2

2

2

1

Bontempo & D'Augelli 2002 [10]

Not known

2

1

2

Case et al. 2004 [11]*

1

2

1

2

Cochran & Mays (2000a) & Mays, Ross (2004) [12, 13]

1

2

2

1

Cochran & Mays (2000b) [14]

1

2

2

1

Cochran et al. 2003 & Mays & Cochran (2001) [15, 16]

2

2

2

1

Faulkner et al. (1998) [17]

Not known

1

1

2

Fergusson et al 1999 [18]*

1

2

1

1

Gilman et al. 2001 [19]

2

2

2

2

Gruskin et al. 2001 [20]

2

1

2

2

Herrell et al. 1999 [21]

Not known

2

1

2

Jorm et al. 2002 [22]

2

1

2

2

King et al. 2003 [1]

1

NA

1

2

Mathy 2002 [23]

1

1

1

2

Mathews et al. 2002 [24]

1

1

1

2

McCabe et al. 2003 [25]

2

1

1

2

Mc Cabe et al. 2004 [26]

2

1

1

1

Nawyn et al. 2000 [27]

Not known

1

1

1

Remafedi et al. 1998 [28]

Not known

2

1

2

Robin et al. 2002 [29]

Not known

2

1

2

Russell & Joyner 2001 [30]

Not known

Not known

1

2

Sandfort et al. 2001 & Sandfort, de Graf, Bijl (2003) [31, 32]

2

2

2

1

Skegg et al. 2003 [33]*

1

2

1

1

Wichstrom & Hegna 2003 [34]*

1

2

1

2

Drabble et al. 2005 [35]

2

Not known

2

2