Table 1.

Principal components to identify the latent variable structure of (unit-scaled) medication non-adherence.

	PC1	PC2	PC3	PC4
(A) Percentage of doses taken	0.98	− 0.18	− 0.03	0.02
(B) Percentage of days on which zero doses were taken	− 0.99	− 0.04	0.10	− 0.09
(C) Percentage of days on which both doses were taken	0.93	− 0.36	0.04	− 0.05
(D) Number of treatment intermissions per 100 study days	− 0.94	− 0.28	0.19	0.07
(E) Duration of treatment intermissions per 100 study days	− 0.93	− 0.23	− 0.29	0.00
Percentage of variance explained	91%	6%	< 1%	< 1%