Table 4.
Model 2, a linear mixed model assessing the interaction effect between atypical event and mean-centered average heart rate (AHR) on perceived stressa.
| Parameter | Perceived stress estimate (β; 95% CI) | t test (df)b | P valuec |
| Intercept | 3.22 (2.62 to 3.83) | 10.7 (45.7) | <.001 c |
| Female sex (reference=male) | 0.117 (−0.498 to 0.731) | 0.383 (40.3) | .70 |
| PGYd 1 (reference=PGY 3) | 0.403 (−0.330 to 1.14) | 1.11 (40.9) | .27 |
| PGY 2 (reference=PGY 3) | −0.289 (−1.03 to 0.448) | −0.792 (39.5) | .43 |
| Hours workede | 0.418 (0.237 to 0.599) | 4.87 (16.9) | <.001 |
| AHRe | 0.032 (0.002 to 0.063) | 2.09 (415) | .04 |
| Negative atypical event (reference=standard day) | 1.40 (0.959 to 1.84) | 6.49 (30.7) | <.001 |
| Atypical event × AHRe | −0.076 (−0.140 to −0.013) | −2.35 (435) | .02 |
aSame as model 1 plus the interaction term. AHR was significantly associated with stress on standard days. This association was attenuated on days with a negative atypical event, as indicated by the significant negative interaction term.
bWald t statistic from SPSS MIXED procedure (Satterthwaite df).
cItalicized values indicate statistical significance (P<.05, 2-tailed).
dPGY: postgraduate year.
eValues are mean centered.