Table 2.
Cluster analysis (k-means): description of the 4-clusters solution and cluster comparisons (ANOVA and Bonferroni test).
| Risky Driving Behaviors | Total | Safe Drivers | Average Drivers | Careless Drivers | Reckless and Impaired Drivers | F Score |
|---|---|---|---|---|---|---|
| n (%) | 2162(100) | 985(45.56) | 471(21.79) | 464(21.46) | 242(11.19) | |
| Talking on phone while driving ° | ||||||
| Mean (SD) | 1.44(0.93) | 1.05(0.27) | 1.28(0.59) | 1.44(0.67) | 3.36(1.26) | 924.1 * |
| 95%C.I. | 1.40–1.48 | 1.04–1.07 | 1.23–1.33 | 1.38–1.50 | 3.21–3.52 | |
| Texting while driving ° | ||||||
| Mean (SD) | 1.67(1.12) | 1.11(0.38) | 1.49(0.77) | 1.82(0.91) | 4.03(0.95) | 1185.1 * |
| 95%C.I. | 1.63–1.72 | 1.09–1.14 | 1.42–1.56 | 1.74–1.90 | 3.91–4.15 | |
| Checking maps on the phone while driving ° | ||||||
| Mean (SD) | 1.26(0.61) | 1.06(0.27) | 1.29(0.56) | 1.41(0.67) | 1.76(1.06) | 114.6 * |
| 95%C.I. | 1.24–1.29 | 1.04–1.08 | 1.24–1.34 | 1.35–1.47 | 1.62–1.89 | |
| Smoking while driving a | ||||||
| Mean (SD) | 1.39(1.01) | 1.07(0.36) | 1.29(0.80) | 1.42(0.95) | 2.85(1.73) | 285.8 * |
| 95%C.I. | 1.35–1.44 | 1.05–1.09 | 1.22–1.36 | 1.33–1.51 | 2.63–3.07 | |
| Eating while driving ° | ||||||
| Mean (SD) | 1.33(0.78) | 1.09(0.38) | 1.25(0.60) | 1.39(0.71) | 2.38(1.36) | 240.7 * |
| 95%C.I. | 1.30–1.37 | 1.06–1.11 | 1.19–1.30 | 1.33–1.46 | 2.21–2.56 | |
| Talking to passenger(s) a | ||||||
| Mean (SD) | 2.79(1.54) | 1.35(0.48) | 3.86(0.87) | 3.85(1.09) | 4.52(0.88) | 2090.8 * |
| 95%C.I. | 2.72–2.85 | 1.32–1.38 | 3.78–3.93 | 3.75–3.95 | 4.41–4.64 | |
| Listening to loud music while driving b | ||||||
| Mean (SD) | 2.17(1.52) | 1.22(0.56) | 1.24(0.43) | 4.02(0.85) | 4.31(1.05) | 2904.2 * |
| 95%C.I. | 2.11–2.24 | 1.19–1.26 | 1.20–1.28 | 3.95–4.10 | 4.17–4.44 | |
| Fatigued driving a | ||||||
| Mean (SD) | 1.49(0.70) | 1.27(0.51) | 1.50(0.66) | 1.58(0.62) | 2.17(1.01) | 133.0 * |
| 95%C.I. | 1.46–1.52 | 1.24–1.31 | 1.44–1.56 | 1.53–1.64 | 2.05–2.30 | |
| Speeding ° | ||||||
| Mean (SD) | 2.10(1.06) | 1.76(0.81) | 2.05(1.00) | 2.28(1.10) | 3.17(1.24) | 141.5 * |
| 95%C.I. | 2.05–2.14 | 1.71–1.82 | 1.96–2.14 | 2.18–2.38 | 3.01–3.32 | |
| Driving under the influence of alcohol c | ||||||
| Mean (SD) | 1.16(0.50) | 1.07(0.29) | 1.13(0.38) | 1.15(0.43) | 1.64(1.00) | 97.4 * |
| 95%C.I. | 1.14–1.18 | 1.05–1.09 | 1.10–1.16 | 1.11–1.19 | 1.51–1.77 | |
| Driving under the influence of drugs c | ||||||
| Mean (SD) | 1.19(0.64) | 1.08(0.39) | 1.12(0.44) | 1.22(0.64) | 1.74(1.23) | 77.9 * |
| 95%C.I. | 1.16–1.22 | 1.06–1.10 | 1.08–1.16 | 1.16–1.28 | 1.58–1.89 | |
* p < 0.001; ANOVA test df (3, 2.162); ° Significant differences (p < 0.001) between the 4 clusters in all the pairwise post hoc comparisons (Bonferroni test); a Significant differences (p < 0.001) between the 4 clusters in all the pairwise post hoc comparisons with the exception of the pairwise comparison between Average Drivers and Careless Drivers; b Significant differences (p < 0.001) between the 4 clusters in all the pairwise post hoc comparisons with the exception of the pairwise comparison between Safe Drivers and Average Drivers; c Significant differences (p < 0.001) between the 4 clusters in all the pairwise post hoc comparisons with the exception of the pairwise comparisons between Safe Drivers and Average Drivers and between Average Drivers and Careless Drivers.