Table 3.

Summary statistics for continuous variables with respect to spinach contamination with generic E. coli

Category and variable	Value
	Total (n = 955)			Positive (n = 63)			Negative (n = 892)
	Mean	Median	IQR	Mean	Median	IQR	Mean	Median	IQR
Human
workers_# (no.)	99.2	100	8–150	99.4	150	8–150	99.2	100	9–150
workers_time (days)	7.7	3	1–9	3	1.5	1.5–4	8.1	3	1–9
toilet_distances (m)	186.9	146.3	45.7–402.3	213.6	201.2	201.2–201.2	185.2	91.4	45.7–402.3
Farm and field conditions
organic_duration (yr)	13.4	4	3–25	20.2	26	25–26	12.5	4	3–25
tillage_time (days)	42.5	17	15–74	24	15	15–15	45.3	18	15–74
Pesticides/fertilizers/irrigation
pesticide_time (days)	24.9	10	5–41	24.7	10	5–41	29.2	12	5–50.8
chemical_time (days)	24.1	15	10–32	24.0	15	10–32	24.8	15	10–44.5
manure_time (days)	228.3	200	200–281	202.4	200	200–200	233.9	224	200–281
manure_age (wk)	12.9	13	9–13	14.6	13	13–13	12.5	13	9–13
compost_time (days)	269.1	275	237–292.5	328	328	328–328	268.6	269	237–291
irrigation_time (days)	12.9	5	2–14	11.4	3.5	3.5–8.5	13	5	2–15
Planting_time (days)	66.8	66	47–82	76.2	77	64–90.5	66.1	65	47–80