An example of coarsened exact matching. UCD: Underlying cause of death; MCD: multiple cause of death; COPD: chronic obstructive pulmonary disease. (1) All deaths with heart failure as the underlying cause of death are identified. In this example, a 60-year-old white male who died in a New Hampshire hospital is identified. (2) All deaths that match the treatment (heart failure) deaths are identified. In this case, all deaths of the same age and sex, with heart failure listed in the causal chain, are identified. (3) The treatment death identified in step 1 is redistributed to the UCDs of the control deaths identified in step 2, proportionally to the number of times each UCD appears among the control deaths. Thus, because 60% of the control deaths identified in step 2 have a UCD of IHD, 60% of the deaths in step 1 are assigned a UCD. The new total of IHD deaths among 60-year-old men is 6.6.