Managing nematodes in Egyptian citrus orchards

Bulletin of the National Research Centre

Table 1 Precision estimates for Tylenchulus semipenetrans population densities based on data derived from citrus orchards^a

Standard error to mean ratio (E)^b	½ confidence interval to mean ratio (D)^b	99% confidence interval+	95% confidence interval++	80% confidence interval+++
Taylor’s power law parameters: a = 0.83, b = 1.95; in stratified random sampling, Egypt
0.17	0.35	1302–3698	1623–3377	1945–3055^t
0.17	0.33	1421–3579	1679–3321	1963–3037^z
Taylor’s power law parameters: a = 1.175, b = 1.95; in systematic sampling, Egypt
20%	42%	1074–3926	1457–3543	1838–3162^t
20%	39%	1216–3784	1523–3477	1861–3139^z
Taylor’s power law parameters: a = 9.2, b = 1.57; in random sampling, Florida, USA
13%	26%	1598–3402	1840–3160	2081–2919^t
13%	25%	1688–3312	1882–3118	2095–2904^z

^aAbd-Elgawad (1992a, b) for citrus in Egypt, and Duncan et al. (1989) for citrus in Florida. Soil sample size of 100 g in Egypt or 100 cm3 in Florida
t and z refer to using Student’s t value and standard normal deviate, respectively
^bE and D values rounded up to nearest two decimals with D at 95% probability