Table 2.
Outcome differences between IS and non-IS groups
| Pre-test | Post-test | Follow-up | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Non-IS | IS | Diff. | Non-IS | IS | Diff. | Non-IS | IS | Diff. | Joint test of intervention group differences | Joint test of time effect | |
| Outcome | Mean (SD) | Mean (SD) | Effect size (p-value) | Mean (SD) | Mean (SD) | Effect size (p-value) | Mean (SD) | Mean (SD) | Effect size (p-value) | p-value | p-value |
| Primary outcomes | |||||||||||
| SEI | .25 (.24) | .17 (.19) | −.29 (.30) | .35 (.23) | .42 (.24) | .48 (.11) | .28 (.21) | .44 (.22) | .86 (.01)* | .02* | <.001* |
| IJA | 2.79 (3.62) | 2.29 (3.16) | −.04 (.89) | 5.00 (7.91) | 7.70 (9.33) | .89 (.08) | 4.42 (4.82) | 8.83 (13.22) | 1.56 (.07) | .30 | <.001* |
| SPA | 3.54 (3.56) | 2.42 (2.93) | −.41 (.31) | 5.33 (6.64) | 6.87 (7.55) | .42 (.41) | 4.96 (5.48) | 7.57 (9.76) | .81 (.27) | .46 | .01* |
| Secondary Outcomes | |||||||||||
| EL T | 25.92 (8.12) | 23.92 (5.50) | −.11 (.71) | 31.92 (13.67) | 34.08 (14.59) | .49 (.18) | 31.36 (12.12) | 34.52 (12.33) | .57 (.24) | .44 | <.001* |
| VR T | 31.12 (9.86) | 27.50 (8.27) | −.27 (.26) | 32.24 (14.07) | 36.75 (14.54) | .57 (.07) | 30.28 (16.62) | 34.44 (16.67) | .46 (.33) | .16 | <.001* |
Effect sizes in Tables 2 and 3 were calculated for each outcome by standardizing the regression-adjusted difference between IS and Non-IS groups by the pooled (IS and Non-IS) standard deviation at pre-test: SEI = 0.21; IJA = 3.33; SPA = 3.19; EL T = 6.82; VR T = 8.93. Regression incorporates adjustment for pre-test values of each outcome variable and other predictors as detailed in the text.