Table 2.

Positive predictions of the causal hypothesis.

no.	prediction	hypothesis
		causation	selective adoption	mixed
1	telomere length for smokers is shorter than telomere length for non-smokers at any time point following the adoption of smoking	yes	yes	yes
2	telomere length prior to adopting smoking is equal in future smokers and non-smokers	yes	no	no
3	rate of telomere attrition is greater in smokers than in non-smokers	yes	no	yes
4	the difference in rates of telomere attrition between smokers and non-smokers is sufficient to explain the difference in telomere length between smokers and non-smokers at any time point following the start of smoking	yes	no	no