Hepatitis C is a blood-borne infection with potentially serious consequences. Identification of social and environmental risk factors is important because Hepatitis C can go undetected for years after infection. A study conducted in Texas in 1991-2 examined whether the incidence of hepatitis C was related to whether people had tattoos and where they obtained their tattoos. Data were obtained from existing medical records of patients who were being treated for conditions that were not blood-related disorders. The patients were classified according to hepatitis C status (whether they had it or not] and tattoo status (tattoo from tattoo parlour, tattoo obtained elsewhere, or no tattoo}. The data are summarised in the following table. Tattoo? Has Hep C No Hep C Tattoo (parlour) 17 35 Tattoo (elsewhere) 8 53 No tattoo 22 491 {a} In any association between hepatitis C status and tattoo status, which variable would be the explanatory variable? Justify your answer. [2] (b) If a simple random sample is not available, a sample may be treated as if it was randomly selected provided that the sampling process was unbiased with respect to the research question. On the information provided above, is it reasonable to treat the data as a random sample for the purposes of investigating a possible relation between tattoos and hepatitis C? Briefly discuss. [2] (c) Assuming that any concerns about data collection can be resolved, test the hypothesis that hepatitis C status and tattoo status are related in the relevant population. If you conclude that there is a relationship, describe it. Use a 1% significance level. [11]