題組內容

2. An outbreak of acute gastroenteritis occurred at a nursing home in Baltimore, Maryland, in December 1980. A total of 46 out of 98 residents of the nursing home became ill. People living in the nursing home shared rooms: 13 rooms contained 2 occupants, 4 rooms contained 3 occupants, and 15 rooms contained 4 occupants. One question that arises is whether or not a geographical clustering of disease occurred for persons living in the same room. A summary of the number of affected people and the total number of people in a room is given in Table 2.

c. (3%) Compare the observed number of rooms with 2 or more affected occupants with the expected number of rooms. Does this comparison give any evidence that clustering of disease occurs within rooms?

Table 2

Number of affected people and total number of people in a room for an outbreak of acute gastroenteritis in a nursing home in Baltimore, Maryland

| People in room | Total number of rooms | Number of rooms with | | | | |
| --- | --- | --- | --- | --- | --- | --- |
| | | 0 affected people | 1 affected person | 2 affected people | 3 affected people | 4 affected people |
| 2 | 13 | 5 | 4 | 4 | 0 | 0 |
| 3 | 4 | 1 | 2 | 0 | 1 | 0 |
| 4 | 15 | 2 | 4 | 3 | 5 | 1 |