Table 1.

Characteristics of trials analyzed

Author	Year	Number
LaPorta 21	1995	40
Pierce 20	1994	26
Gomaa 22	2003	90
Mahajan 11	2009	90
Cooper 6	2002	147
Moran 19	1991	60
Alahuhta 13	1992	19
Hall 5	1994	30
Thomas 4	1996	40
Ayorinde 14	2001	108
Ngan Kee 18	2008	125
Magalhães 10	2009	60
Dyer 17	2009	40
Prakash 16	2010	60
Adigun 15	2010	62