Table 1. Joint Associations of Sensation Seeking and Impulsivity with Outcome Variables, Unadjusted for Sociodemographic Factors.
| Outcome Variable and Effective Sample Size |
Sensation Seeking Estimate of exp[b1], (95% CI), p |
Impulsivity Estimate of exp[b2], (95% CI), p |
Interaction Estimate of exp[b3], (95% CI), p |
|---|---|---|---|
| Partners in last yeara (n=2,350) |
1.23, (1.16–1.31), p<.0001 | 1.22, (1.13–1.33), p<.0001 | 0.98, (0.90–1.07), p=.6731 |
| Partners in lifetimea (n=2,330) | 1.16, (1.08–1.24), p<.0001 | 1.17, (1.07–1.28), p=.0006 | 0.98, (0.90–1.07), p=.6646 |
| Unprotected acts in last 30 daysa (n=1,903) |
1.06, (0.95–1.19), p=.3142 | 1.31, (1.14–1.52), p=.0002 | 0.96, (0.83–1.10), p=.5163 |
| Acts using alcohol in last 3 monthsb (n=2,382) |
5 vs. 1: 3.62, (2.16–6.07) | 5 vs. 1: 1.53, (0.68–3.42) | 5 vs. 1: 0.72, (0.33–1.57) |
| 4 vs. 1: 3.00, (2.18–4.13) | 4 vs. 1: 3.74, (2.22–6.32) | 4 vs. 1: 0.54, (0.32–0.92) | |
| 3 vs. 1: 1.74, (1.40–2.17) | 3 vs. 1: 1.92, (1.49–2.48) | 3 vs. 1: 0.95, (0.71–1.26) | |
| 2 vs. 1: 1.32, (1.04–1.68), p<.0001 | 2 vs. 1: 1.10, (0.85–1.43), p<.0001 | 2 vs. 1: 0.84, (0.62–1.13), p=.1662 | |
| Acts using drugs in last 3 monthsb (n=2,383) |
5 vs. 1: 2.82, (1.38–5.74) | 5 vs. 1: 1.35, (0.43–4.30) | 5 vs. 1: 0.99, (0.36–2.73) |
| 4 vs. 1: 1.76, (1.26–2.45) | 4 vs. 1: 5.07, (2.73–9.42) | 4 vs. 1: 0.29, (0.15–0.55) | |
| 3 vs. 1: 1.59, (1.28–1.97) | 3 vs. 1: 2.50, (1.79–3.48) | 3 vs. 1: 0.72, (0.51–1.02) | |
| 2 vs. 1: 1.52, (1.17–1.98), p<.0001 | 2 vs. 1: 1.63, (1.12–2.38), p<.0001 | 2 vs. 1: 0.72, (0.49–1.08), p=.0017 | |
| Acts with partner who had an STD in last 3 monthsb (n=2,377) |
4 vs. 1: 0.84, (0.48–1.45) | 4 vs. 1: 1.28, (0.65–2.55) | 4 vs. 1: 0.40, (0.17–0.95) |
| 3 vs. 1: 0.62, (0.38–1.02) | 3 vs. 1: 2.04, (1.09–3.84) | 3 vs. 1: 0.68, (0.32–1.46) | |
| 2 vs. 1: 1.48, (1.22–1.79), p<.0001 | 2 vs. 1: 1.25, (0.96–1.62), p=.0594 | 2 vs. 1: 1.02, (0.79–1.33), p=.1528 | |
| Acts with partner who injected drugs in last 3 monthsb (n=2,377) |
4 vs. 1: 2.16, (0.71–6.57) | 4 vs. 1: 1.36, (0.24–7.62) | 4 vs. 1: 1.56, (0.41–5.93) |
| 3 vs. 1: 1.51, (0.60–3.80) | 3 vs. 1: 1.42, (0.40–5.08) | 3 vs. 1: 1.93, (0.76–4.91) | |
| 2 vs. 1: 1.15, (0.87–1.54), p=.3297 | 2 vs. 1: 2.00, (1.31–3.07), p=.0150 | 2 vs. 1: 0.83, (0.54–1.29), p=.3798 | |
| Acts with non-monogamous partner in last 3 monthsb (n=2,377) |
4 vs. 1: 1.57, (1.17–2.12) | 4 vs. 1: 1.21, (0.81–1.80) | 4 vs. 1: 0.98, (0.65–1.47) |
| 3 vs. 1: 1.50, (1.21–1.87) | 3 vs. 1: 1.44, (1.07–1.94) | 3 vs. 1: 0.94, (0.69–1.28) | |
| 2 vs. 1: 1.48, (1.18–1.86), p<.0001 | 2 vs. 1: 1.44, (1.06–1.97), p=.0204 | 2 vs. 1: 0.92, (0.67–1.26), p=.9498 | |
| Acts with partner who has sex with both men and women in last 3 monthsb (n=2,377) |
4 vs. 1: 1.97, (1.35–2.87) | 4 vs. 1: 1.60, (0.88–2.90) | 4 vs. 1: 1.04, (0.60–1.79) |
| 3 vs. 1: 2.45, (1.66–3.60) | 3 vs. 1: 1.15, (0.63–2.10) | 3 vs. 1: 1.07, (0.62–1.84) | |
| 2 vs. 1: 1.17, (0.88–1.55), p<.0001 | 2 vs. 1: 1.73, (1.16–2.58), p=.0260 | 2 vs. 1: 0.71, (0.46–1.10), p=.4790 | |
| Acts with partner using alcohol in last 3 monthsb (n=2,310) |
4 vs. 1: 2.04, (1.50–2.79) | 4 vs. 1: 4.08, (2.45–6.78) | 4 vs. 1: 0.46, (0.27–0.77) |
| 3 vs. 1: 1.54, (1.24–1.90) | 3 vs. 1: 1.63, (1.26–2.10) | 3 vs. 1: 0.86, (0.66–1.13) | |
| 2 vs. 1: 1.06, (0.84–1.35), p<.0001 | 2 vs. 1: 1.08, (0.83–1.41), p<.0001 | 2 vs. 1: 0.66, (0.49–0.89), p=.0034 | |
| Acts with partner using drugs in last 3 monthsb (n=2,354) |
4 vs. 1: 1.38, (1.00–1.92) | 4 vs. 1: 4.08, (2.31–7.23) | 4 vs. 1: 0.41, (0.22–0.75) |
| 3 vs. 1: 1.21, (0.98–1.50) | 3 vs. 1: 2.32, (1.70–3.18) | 3 vs. 1: 0.73, (0.52–1.01) | |
| 2 vs. 1: 1.35, (1.06–1.71), p=.0203 | 2 vs. 1: 1.55, (1.11–2.14), p<.0001 | 2 vs. 1: 0.87, (0.62–1.22), p=.0128 |
Note. exp[b1], exp[b2], and exp[b3] are defined in the Data Analysis section of the article.
CI = confidence interval; STD = sexually transmitted disease.
The results in these rows are based on negative binomial regression models. To exemplify their interpretation, consider the outcome of partners in the last year. Among people with an impulsivity score of 3, a one-unit increase in sensation seeking corresponds to an estimated 23% increase in the mean number of partners in the last year (because the estimate of exp[b1] = 1.23). Among people with a sensation seeking score of 3, a one-unit increase in impulsivity corresponds to an estimated 22% increase in the mean number of partners (because the estimate of exp[b2] = 1.22). Among people with an impulsivity score of 4, a one-unit increase in sensation seeking corresponds to an estimated 21% increase in the mean number of partners (because the estimate of exp[b3] × exp[b1] = 1.21 and exp[b3] is the factor by which exp[b1] is multiplied to compare people one unit apart on sensation seeking when their common impulsivity score is increased from 3 to 4).
The results in these rows are based on generalized logit regression models. Labels of “2 vs. 1” pertain to odds-like quantities involving the second and first categories of the outcome variable, labels of “3 vs. 1” pertain to odds-like quantities involving the third and first categories, and so forth. To exemplify interpretation of the results, consider the outcome of acts using alcohol in the last three months. Among people with an impulsivity score of 3, a one-unit increase in sensation seeking corresponds to an estimated 74% increase in the odds-like quantity involving the third and first categories of acts using alcohol in the last three months (because the estimate of exp[b1] = 1.74). Among people with a sensation seeking score of 3, a one-unit increase in impulsivity corresponds to an estimated 92% increase in the odds-like quantity (because the estimate of exp[b2] = 1.92). Among people with an impulsivity score of 4, a one-unit increase in sensation seeking corresponds to an estimated 65% increase in the odds-like quantity (because the estimate of exp[b3] × exp[b1] = 1.65 and exp[b3] is the factor by which exp[b1] is multiplied to compare people one unit apart on sensation seeking when their common impulsivity score is increased from 3 to 4).