Table 4

Findings of higher quality studies

	Conclusion of negative impact?
	Yes	No	χ²	p Value
Meeting all four Siegel criteria (n=21)	0% (0/21)	100% (21/21)^5,^25,^29,^30,^34–³⁶ ^42–^46,^48,^49,^51–^56,⁹⁸	15.13	0.000
Including an objective measure (n=37)	19% (7/37)^18,^27,^57–⁶¹	81% (30/37)^5,^25,^29,^30,^33–^56,^98,¹¹³	7.64	0.006

Funded by source clearly independent of the tobacco industry (n=60)	0% (0/60)	100% (60/60)^5,^24–^26,^28–^30,^32–^56,^62–^79,^98,^100–^102,^109–^113,¹¹⁵	82.38	0.000
Peer reviewed (n=24)	4% (1/24) ⁸⁴	96% (23/24) ^5,^35,^42,^44–^49,^54,^56,^63–^66,^72,^75–^77,^98,^101,¹¹⁵	14.09	0.000