Table 3

Hypothetical data from 10 ambulance records and 20 emergency department records

Ambulance data							Emergency department data
Case	Year	Day	Hosp	Birth year	Birthday	Sex	Case	Year	Day	Hosp	Birth year	Birthday	Sex
From past experience or calculations using the larger list, we might assume that: (1) About 90% of injured patients brought by ambulance will generate an emergency department record, so the prior probability of a match between records on the two lists might be about 0.045 (equation 6), and the prior odds (equation 1) about 0.047. (2) The chances that records truly from the same event will have the same admission year, admission date, hospital, birth year, birth date, and sex (the M probabilities) might be 0.99, 0.95, 0.99, 0.95, 0.99, and 0.95 respectively. (3) The chances that variables would match for randomly selected records (the U probabilities) might be 0.50 for admission year, 0.0027 (1/365) for admission date, 0.4 for hospital X or Y, 0.2 for hospital Z, 0.01 for birth year, 0.0027 for birth date, 0.60 for males, and 0.40 for females.
A01	01	Jan01	X	1950	Jan21	M	E01	01	Jan01	X	1950	Jan21	M
A02	01	Jan01	X	1950	May01	F	E02	01	Jan10	Z	1987	Jul17	M
A03	01	Jan10	Y	1975	Dec27		E03	01	Feb23	X	1992	Oct19	M
A04	01	Aug13	X	1977	Apr29	F	E04	01	Apr22	Y	1979	May09	M
A05	01	Sep12	Y	1980	Feb16	F	E05	01	May02	X	1929	Nov12	F
A06	01	Dec31	Z	1919	Sep16	M	E06	01	May23	Y	1964	Dec01	M
A07	02	Feb02	X	1924	Mar26	F	E07	01	Jun01	X	1950	May01	F
A08	02	Jun10	Y	1951	Mar29	M	E08	01	Aug14	X	1977	Apr29	F
A09	02	Aug06	Y	1953	Apr17		E09	01	Sep12	Y	1980	Feb16	F
A10	02	Sep21	Z	1956	Jun03	F	E10	01	Oct21	Y	1985	Mar12	M
							E11	02	Jan01	Z	1919	Sep16	M
							E12	02	Jan10	Y	1975	Dec27	F
							E13	02	Feb02	X	1924	Mar26	F
							E14	02	May16	X	1924	Oct12	M
							E15	02	Jun10	Y	1951	Mar29	M
							E16	02	Jul04	Z	1982	Jun12	M
							E17	02	Aug05	Y	1953	Apr17	M
							E18	02	Aug06	Y	2002	Apr17	F
							E19	02	Sep21	Z	1956	Jun03	F
							E20	02	Nov22	X	1917	May29	M