A study was conducted to investigate cancer occurrence among workers exposed to chemicals in the shoe manufacturing industry. In 1975, the study identified a total of 1573 shoemakers who had worked in the industry for more than 2 years in the 1960s in the personnel records of several large shoe manufacturing companies. Through data linkage to the National Cancer Registry, the study found that a total of 55 cancer cases among the shoemakers were reported from 1970 to 1990. In addition, 67 cancer cases were also identified among a comparable group of 3635 office workers employed in the shoe companies during the same period. a) What was the study design used in this example? State two reasons to justify your choice of study design. (2 marks) b) Draw up a 2x2 table including correct labels and totals. Calculate a suitable measure of association and interpret your result. (Please show working out in your answer) (4 marks) c) What is the attributable fraction (attributable risk percent)? How would you interpret this result? (2 marks)