1) A sample size of 50 health centers would allow estimating the proportion of health centers providing tuberculosis screening with a 10% margin of error at a 95% confidence level, assuming a proportion of 50%. 2) A sample size of 600 adults would allow estimating the prevalence of cough with a 2% margin of error, accounting for a design effect of 2 and 10% non-response rate. 3) A sample size of 500 small-scale industry workers and 1,000 medium-scale industry workers would allow detecting a risk ratio of 1.5 for work-related injuries between the two groups with 80% power and 5%