Table 2. Estimated marginal means (standard deviations) for primary and secondary outcome measures and within- and between-group effect sizes for internet cognitive–behavioural therapy (iCBT) and waiting list control groups.
| Pre-treatment (iCBT, n=27, control, n=36) | Mid-treatment | Post-treatment (iCBT, n=16, control, n=31) |
t(df) Pre-treatment comparisons |
F(df) Within-group comparison |
F(df) Between-group comparison |
r (for within-group ES) | Effect size Hedges g (95% CI) Within-group | Effect size Hedges g (95% CI) Between-group (post) | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Measure | n | M | s.d. | M | s.d. | M | s.d. | ||||||
| PDSS-SR iCBT | 27 | 13.00 | 5.73 | 7.90 | 5.45 | 6.36 | 5.20 | t(57)=−0.54, P=0.59 | F(2,96.61)=23.51, P<0.001 | F(2,95.92)=14.14, P<0.001 | 0.48 | 1.24 (0.55−1.92) | 0.97 (0.34−1.61) |
| Control | 36 | 12.14 | 5.74 | 12.39 | 5.62 | 11.75 | 5.57 | F(2,94.63)=0.33, P=0.72 | 0.73 | 0.08 (−0.41 to 0.56) | |||
| K10 iCBT | 27 | 24.04 | 7.15 | 18.24 | 6.76 | 17.43 | 6.44 | t(55)=0.73, P=0.47 | F(2,96.96)=16.64, P<0.001 | F(2,95.96)=9.03, P<0.001 | 0.20 | 1.29 (0.60 to 1.98) | 0.92 (0.28 to 1.55) |
| Control | 36 | 25.58 | 7.34 | 26.14 | 7.07 | 23.80 | 7.02 | F(2,94.19)=3.12, P=0.049 | 0.83 | 0.18 (−0.30 to 0.67) | |||
| PHQ-9 iCBT | 27 | 8.33 | 4.90 | – | – | 4.64 | 4.64 | t(55)=0.79, P=0.43 | F(1,52.02)=10.84, P<0.01 | F(1,50.40)=3.91, P=0.053 | 0.01 | 1.16 (0.48 to 1.84) | 0.79 (0.17 to 1.41) |
| Control | 36 | 9.40 | 4.91 | – | – | 8.45 | 4.79 | F(1,47.55)=1.28, P=0.26 | 0.70 | 0.16 (−0.33 to 0.64) | |||
| WHODAS-II iCBT | 27 | 25.42 | 7.99 | – | – | 20.26 | 7.16 | t(55)=0.51, P=0.61 | F(1,48.47)=15.11, P<0.001 | F(1,47.48)=10.09, P<0.01 | 0.47 | 1.00 (0.33 to 1.67) | 0.81 (0.19 to 1.44) |
| Control | 36 | 26.51 | 8.22 | – | – | 26.58 | 7.85 | F(1,45.69)=0.00, P=0.95 | 0.85 | 0.00 (−0.48 to 0.48) | |||
| NEO iCBT | 27 | 30.92 | 7.94 | – | – | 26.63 | 6.96 | t(56)=−0.54, P=0.59 | F(1,48.91)=12.36, P<0.001 | F(1,48.21)=4.04, P=0.05 | 0.40 | 0.96 (0.30 to 1.63) | 0.25 (−0.35 to 0.86) |
| Control | 36 | 29.79 | 8.05 | – | – | 28.57 | 7.74 | F(1,47.01)=1.81, P=0.19 | 0.92 | 0.10 (−0.39 to 0.58) | |||
NEO, NEO Five Factor Personality Inventory, Neuroticism Scale; PDSS-SR, Panic Disorder Severity Scale Self-Report Version; PHQ-9, The Patient Health Questionnaire-9; K-10, Kessler 10-Item Psychological Distress Scale; WHODAS-II, The 12-Item World Health Organization Disability Assessment Schedule; iCBT, internet-based cognitive–behavioural therapy group.