4.4. Additional sensitivity analysis
In the following sensitivity analysis, we only report IV results
using two IVs: live in the same building and on the same floor.
However, all IV results are robust to using different sets of instruments.
Rather than operating through risk perceptions, the relationship
between smoking cessation and knowing the 2011-diagnosed
smoker could reflect a peer effect. Neighbors who regularly smoke
with the lung cancer patient are presumably good friends. So the
fact that a friend is diagnosed with lung cancer may not only affect
the smoker’s risk perceptions but also affect the propensity to
smoke because the friend with lung cancer patients can no longer
smoke with him, a peer effect.
To investigate whether the change in smoking behavior of
men could have been affected by loss of a smoking companion
rather than by a change in risk perceptions, we drop 122
men who smoked with the lung cancer patient at least once
monthly (Appendix table* 5, Panel A) and alternatively, we drop
168 male smokers who smoked with the lung cancer patient at
least once per six month period (Panel B). The statistical significance
on the risk perception covariates is unaltered. Each
parameter estimate remains statistically significant at 0.05 or
less.