  We investigate the prevalence rate of smoking in Covid-19 patients and
examine whether there is a difference in the distribution of smokers between
the two statistical populations of critically ill patients with Covid-19 and
the entire Iranian population or not. To do this, we first prepared a sample of
1040 Covid-19 patients admitted to hospitals in Tehran, Rasht, and Bojnord.
Then, through the non-parametric statistical runs test, we show that the sample
was randomly selected, and it is possible to generalize the result of tests on
the sample to the community of hospitalized Covid-19 patients. In continuation,
we examined the hypothesis that the smoking prevalence among Covid-19 patients
admitted to hospitals is equal to the prevalence rate of smoking in Iranian
society. For this purpose, we used the non-parametric chi-square test, and it
was observed that this hypothesis is rejected. The data show a significant
difference in the prevalence of smoking between critically ill Covid-19
patients and the whole of Iranian society. Additionally, we examined this
hypothesis in some subpopulations, and the results were the same.
