Table 4.
Association between SHS exposure and cognitive performance test (digit span, letter–number sequencing, coding and symbol search) (N=312)
| Cognitive tests | Group | n | Adjusted mean (95% CI) | F statistic (df) | p a |
|---|---|---|---|---|---|
| Digit span | Exposed | 174 | 11.10 (10.30–11.91) | 26.54 (1305) | 0.010 |
| Non-exposed | 138 | 13.54 (12.66–14.42) | |||
| Letter–number sequencing | Exposed | 174 | 10.20 (9.26–11.15) | 0.66 (1305) | 0.422 |
| Non-exposed | 138 | 10.65 (9.62–11.69) | |||
| Coding | Exposed | 174 | 40.22 (38.16–42.29) | 0.52 (1305) | 0.468 |
| Non-exposed | 138 | 41.09 (38.84–43.34) | |||
| Symbol search | Exposed | 174 | 24.83 (23.58–26.07) | 0.46 (1305) | 0.503 |
| Non-exposed | 138 | 25.32 (23.96–26.69) |
a
Test of between subject effects.
Multifactorial MANCOVA Pillai’s Trace=0.084, F statistic (df)=6.80 (4302), p<0.001; with adjustment for gender, parents’ educational levels, family income and academic performance. Assumption of multivariate normal distribution, homogeneity of variance and covariance, multicollinearity, linearity between study factor and covariate were all fulfilled.