Table 3. Altitude and source effects on rates of maize seed-lot replacement (1−p) and diffusion (q) in Mexico¹.

Altitude	Replacement by source location2 (N = 744)			Replacement by source type2 (N = 744)				Diffusion by source location2 (N = 739)			Diffusion by ownership3 (N = 739)
	local	introduced	total	informal	grain	formal	total	local	Introduced	total	own	new	total
Low (<1200masl)	0.24	0.81	0.31	0.24	0.56	1.00	0.31	0.22	0.08	0.21	0.23	0.17	0.21
Mid (1200–2000masl)	0.21	0.62	0.36	0.25	0.58	0.91	0.36	0.19	0.09	0.15	0.19	0.10	0.15
High (>2000masl)	0.17	0.67	0.23	0.20	0.80	0.83	0.23	0.22	0.21	0.22	0.25	0.14	0.22
Total	0.20	0.67	0.28	0.22	0.63	0.93	0.28	0.22	0.13	0.20	0.23	0.14	0.20
G source/ownership effects	105.5** (3 df)			28.8** (3 df)				6.2* (3 df)			7.7** (3 df)
G altitude effect	7.72* (4 df)			3.54 (3 df)				4.5 (4 df)			3.1 (4 df)

Significant at the 0.05 level is indicated by **; significance at the 0.10 level is indicated by *. G-tests exclude seed from formal seed systems; masl: meters above sea level.

¹Expressed as a ratio, rates vary between 0 and 1. Replacement implies that seed is not saved by a farmer across cycles; diffusion entails the exchange of saved seed among farmers.

²The terms “local” and “introduced” refer to the location of the immediate source of seed; e.g., seed is local if acquired from neighbors, while seed acquired from farmers in another locality is introduced.

³Seed acquired during the current cycle is “new;” seed saved by the farmer from a previous cycle is his/her “own.”