{"id":152,"date":"2022-01-31T08:00:00","date_gmt":"2022-01-31T08:00:00","guid":{"rendered":"https:\/\/www.lancaster.ac.uk\/stor-i-student-sites\/danielle-notice\/?p=152"},"modified":"2024-03-10T16:46:13","modified_gmt":"2024-03-10T16:46:13","slug":"lead-probably-not-in-my-water-zero-inflated-models","status":"publish","type":"post","link":"https:\/\/www.lancaster.ac.uk\/stor-i-student-sites\/danielle-notice\/2022\/01\/31\/lead-probably-not-in-my-water-zero-inflated-models\/","title":{"rendered":"Lead (probably not) in my water: zero-inflated models"},"content":{"rendered":"Reading Time: <\/span> 5<\/span> minutes<\/span><\/span>\n
\"\"<\/figure><\/div>\n\n\n\n

It’s interesting that there are some problems that the younger generation, if they even know it exists, assume have been dealt with completely. That’s what I thought about lead piping. Yet the University of Edinburgh and Scottish Water have ongoing research related to this.<\/p>\n\n\n\n

It became relatively common knowledge in the 1970s that lead is dangerous. However before its harmful health effects were discovered, lead was commonly used in water pipes. In Scotland, the water supplies do not naturally have high lead levels. Since the banning of lead pipes in 1969, Scottish Water has worked to remove lead pipes from the mains distribution system although some pipes carrying water to customers\u2019 houses may still be made of lead and require replacement. Additionally, properties built before 1970 are at higher risk of containing internal lead piping or tanks and having contaminated tap water.<\/p>\n\n\n\n

  1. What is the problem?<\/li>
  2. What is count regression?<\/li>
  3. Why a zero-inflated model?<\/li>
  4. Other considerations<\/li><\/ol>\n\n\n\n

    1. So just find and replace all the pipes…<\/h2>\n\n\n\n

    In a world without limitations, Scottish Water would visit every household built before 1970 and test their tap water for lead-contamination. However that is not possible in reality. So instead it makes sense to model which areas (for example postcodes) have more houses with lead-contaminated water so that sampling efforts can be focused there. The goal is to identify the possible factors which increase the risk of more households in a postcode returning water samples with lead concentration greater than 1\u03bcg\/L.<\/p>\n\n\n\n

    Data<\/h3>\n\n\n\n

    To look at this problem, we consider data containing 308 observations, each representing a different postcode. The variables included are:<\/p>\n\n\n\n