Table 4 Tested hypotheses on construct validity: Consequences of involvement in care

Burden

A moderate to strong negative association with measures of caregivers' burden.

1. Association with caregivers' burden:

r = -0.69, 95% Confidence Interval (CI): -[1.00, 0.62]; n = 82.

2. Categories of burden:

-equal distances: 31.4 (SPPIC 0–3, n = 45), 26.7 (SPPIC 3–6, n = 25), to 19.4 (SPPIC 6–9, n = 12);

F = 38.850, p < 0.001;

-equal observations: 32.0 (1, n = 21), 31.0 (2, n = 18), 28.8 (3, n = 23), 21.1 (4, n = 20); F = 24.452, p < 0.001.

Mental quality of life

A moderate to strong positive association with measures of caregivers' mental quality of life.

1. Association with caregivers' depressive symptoms:

r = 0.44, 95% CI: [0.14, 0.57]; n = 88

2. Categories of mental quality of life:

-equal distances: 23.5 (MCS 0–33.3, n = 8), 26.0 (MCS 33.3–49.9, n = 27), to 30.1 (MCS 49.9–100.0, n = 53);

F = 7.615, p = 0.001;

-equal observations: 24.6 (1, n = 22), 28.1 (2, n = 22), 28.1 (3, n = 22), 32.2 (4, n = 22); F = 6.462, p = 0.001.

Depressive symptoms

A moderate to strong negative association with depressive symptoms.

1. Association with caregivers' depressive symptoms:

r = -0.27, 95% CI: -[0.49, -0.06]; n = 88

2. Categories of depressive symptoms:

-dichotomised: 27.7 (CES-D ≥ 16.0, n = 18), 28.3 (CES-D < 16, n = 68),

student's t-test: p = 0.716.

Mastery

A moderate to strong positive association with mastery.

1. Association with caregivers' mastery:

r = 0.34, 95% CI: [0.14, 0.57]; n = 85

2. Categories of mastery:

-equal distances: 24.9 (mastery 16–21, n = 18), 28.5 (mastery 21–28, n = 45), to 30.9 (mastery 28–35, n = 21);

-equal observations: 25.9 (1, n = 23), 28.5 (2, n = 21), 28.2 (3, n = 19), 30.9 (4, n = 21).