Research Article
Modeling Count Outcomes from HIV Risk Reduction Interventions: A Comparison of Competing Statistical Models for Count Responses
Table 2
The estimated parameters, coefficients of the Poisson, NB, ZIP, and ZINB models for all vaginal sex episodes outcome at 12 months.
| Parameter | Poisson | Negative binomial | Zero-inflated poisson | Zero-inflated negative binomial | Poisson | Logit | NB | Logit |
| Intercept | 1.5424* | 1.7947* | 2.0453 | −0.8089 | 2.0630* | −0.1824 | Age | 0.0491* | 0.0290 | 0.0392* | −0.0476 | 0.0252 | −0.0781 | white | 0.1406* | 0.1914 | 0.1077* | −0.0588 | 0.1863 | 0.0773 | Multiracial | 0.4249* | 0.3576** | 0.3165* | −0.8917 | 0.2679 | −1.0362 | Other race | 0.0275 | −0.0222 | 0.2054 | 0.1203 | 0.0388 | 0.3403 | Hispanic | −0.2908* | −0.1882 | −0.1976* | 0.5028 | −0.1406 | 0.4350 | Poverty | 0.2060* | 0.2899* | 0.1600* | −0.3786 | 0.2232* | −0.4106 | Baseline | 0.0163* | 0.0181* | 0.0147* | −0.0206* | 0.0159* | −0.0227 | Condition | −0.1542* | −0.2062** | −0.1400* | 0.1227 | −0.1911* | 0.0813 | Dispersion | | 1.3873* | | | 0.8370* | | Lagrange multiplier | 63120.17* | | | | | | −2 Log Likelihood | 9244.29 | 3512.26 | 7344.30 | | 3474.70 | | Parameter | 9 | 10 | 18 | | 19 | | AIC | 9262.29 | 3532.26 | 7380.00 | | 3512.70 | | BIC | 9299.83 | 3573.98 | 7455.10 | | 3591.90 | | Vuong test | | | 7.6369* | | 3.2400* | |
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*Indicates that the coefficients are significant at 5%; **the coefficients are significant at 10%.
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