Table 2.

The mean (SD) precision (mm), and precision interval (all calculated from double examinations) in measuring acetabular cup translation in the x-, y-, and z-planes. The precision is defined by the SD × critical value (t) and the precision interval is defined by the mean (SD) × t

Method / Plane	Mean (SD)	Precision	Precision interval
Liner (n = 44)
x	−0.002 (0.079)	0.161	−0.163 to 0.159
y	−0.004 (0.520)	0.105	−0.109 to 0.102
z	−0.021 (0.227)	0.457	−0.478 to 0.436
Shell (n = 47)
x	−0.011 (0.148)	0.298	−0.309 to 0.287
y	0.024 (0.138)	0.278	−0.255 to 0.302
z	−0.023 (0.311)	0.626	−0.649 to 0.603
Shell + liner (n = 45)
x	−0.007 (0.091)	0.184	−0.191 to 0.177
y	0.003 (0.054)	0.108	−0.105 to 0.111
z	−0.023 (0.197)	0.397	−0.421 to 0.374