Table 3. A hypothetical data layout for a study of the short-term effects of particulate matter on daily mortality.

Day	No. of deaths	PM2.5 (µg/m3)	Temperature (°C)	…
1	18	23.6	9.3
2	16	23.8	13.2
3	16	22.2	13.7
4	20	18.8	11.3
5	11	23.1	13.8
6	21	28.6	15.4
…	…	…	…	…

Abbreviation: PM_2.5, particulate matter less than 2.5 microns in aerodynamic diameter.