Table 2.
Summary of results of Rasch analysis: original and revised subscales during pregnancy and postpartum
| Subscale | Analysis | Item No. | Overall model fit | Item fit residual mean (SD) |
Person fit residual mean (SD) |
PSI | Cronbach alpha | % sig t-testsa |
|---|---|---|---|---|---|---|---|---|
| Pregnancy (Baseline) | ||||||||
| Original Mental health (4 items) | 1 | 2, 4, 5, 10 | Chi sq. = 14.21 df = 16, p = .58 | .12 (2.35) | −.44 (1.22) | .79 | .83 |
5.24% (CI: 2.8–7.8) |
| Revised Mental Health (remove item 10) | 2 | 2, 4, 5 | Chi sq. = 11.79, df = 9, p = .22 | −.01 (1.12) | −.52 (1.01) | .77 | .84 | 3.65% |
| Revised Mental Health (add item 9) | 3 | 2, 4, 5, 9 | Chi sq. = 8.45, df = 16, p = .93 | −.21 (.82) | −.63 (1.27) | .84 | .88 |
5.4% (CI: 2.8–8.0) |
| Original Physical Health (4 items) | 4 | 3, 6, 7, 8 | Chi sq. = 19.03, df = 16, p = .27 | −.09 (1.06) | −.37 (.99) | .64 | .69 | 2.63% |
| Revised Physical Health (add item 1) | 5 | 1, 3, 6, 7, 8 | Chi sq. = 29.14, df = 20, p = .08 | −.12 (1.45) | −.39 (1.09) | .74 | .76 | 3.62% |
| Postpartum (26-weeks) | ||||||||
| Revised Mental Health | 6 | 2, 4, 5, 9 | Chi sq. = 13.86, df = 12, p = .31 | −.18 (1.0) | −.48 (1.01) | .84 | .87 | 3.65% |
| Revised Physical Health | 7 | 1, 3, 6, 7, 8 | Chi sq. = 34.82, df = 15, p = 0.02 | −.62 (2.08) | −.42 (.88) | .72 | .75 |
5.6% (CI: 2.8–8.4) |
Chi sq chi-square, df degrees of freedom, p probability, PSI person separation index, CI confidence interval
aConfidence interval only reported if the % value exceeds 5%