Overdisp: A Stata (and Mata) Package for Direct Detection of Overdispersion in Poisson and Negative Binomial Regression Models

Fávero, Luiz Paulo Lopes; Belfiore, Patrícia; Santos, Marco Aurélio dos; Souza, Rafael de Freitas

doi:10.19139/soic-2310-5070-557

Cited by 18 publications

(13 citation statements)

References 10 publications

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“…We estimated a correlated random effects negative binomial model that accounts for overdispersion in the dependent variable conditional on the explanatory variables. When overdispersion is detected, the negative binomial model may provide a better fit than a Poisson model (Cameron & Trevidi, 2013;Fávero et al, 2020;Yang et al, 2009), which assumes that the mean equals the variance for the dependent variable.…”

Section: Analytical Approachmentioning

confidence: 99%

Household livelihood diversification in rural Africa

Musumba

Palm

Komarek

et al. 2022

Agricultural Economics

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Diversification is a common livelihood strategy for rural households in developing countries, with diversification being either a choice or necessity depending on individual household contexts. Using two waves of data (from 2009 and 2011) for 1773 households from eight countries in sub-Saharan Africa, we examined livelihood diversification and its drivers. We examined livelihood diversification by considering household involvement in three livelihood activities: crop, livestock, and non-farm. Results indicated that 40% of households conducted all three livelihood activities, but there was heterogeneity in diversity levels. We used a correlated random effects model to identify the factors that pushed or pulled households to diversify their activities. Access to non-agricultural credit was positively associated with livelihood diversity as it can catalyze involvement in non-farm activities. Drought had a negative effect on livelihood diversity. Area of crop land had a positive effect on the number of livelihood activities conducted. We found that 53% of households added or removed at least one livelihood activity between 2009 and 2011, and the addition of non-farm activities was the most common change. Our results demonstrated the dynamic nature of livelihoods and importance of shocks (such as drought) and resource endowments (land) in understanding household livelihood diversification.

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Section: Analytical Approachmentioning

confidence: 99%

Household livelihood diversification in rural Africa

Musumba

Palm

Komarek

et al. 2022

Agricultural Economics

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“…The 95% confidence intervals and the p -values for the 1, 5 and 10% levels of statistical significance are likewise reported. Following Fávero et al . (2020), we use the overdisp command in Stata to test for overdispersion.…”

Section: Resultsmentioning

confidence: 99%

Determinants of maternal healthcare-seeking behaviours in Ghana

Bawuah

Ampaw

2022

IJSE

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PurposeThis paper aims to explore the determinants of maternal healthcare services (MHS) utilisation in Ghana.Design/methodology/approachIn this paper, logit and negative binomial regressions were used to model data from a recent nationally representative survey (the 2017 Ghana Maternal Health Survey). The analysis is observational, without causal implications. The authors measure MHS utilisation by four indicators: antenatal care (ANC) use, the number of ANC clinic visits, choice of health facility delivery and postnatal care (PNC) use.FindingsAge, parity, education, marital status, wealth, residence and health facilities concentration proved to be significant predictors of MHS use in Ghana. Specifically, older, married and educated women; women of lower parity; those living in urban areas and women from wealthier households were more likely to use MHS. The authors also find that health facilities and personnel predicted higher MHS use. Lastly, women with frequent stillbirths had higher MHS use.Practical implicationsThe results for health facilities and personnel suggest that increasing the supply of health centres and workers may enhance MHS use. The authors conclude that women of lower socio-economic status have worse MHS use, meaning empowering such women might increase such women's MHS use.Originality/valueExisting data suggest falling MHS use in Ghana. Yet, the extant works are based on relatively old data or lack external validity (besides using limited MHS indicators). This paper provides recent and generalisable evidence for public health policies. Additionally, this paper tests the statistical significance of some supply-side factors that have yet to be emphasised in the literature.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/IJSE-03-2022-0199.

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“…A sensitivity analysis was performed on the study outcomes excluding people with previous SARS-CoV-2 infection, who might have had an increased risk of various disease diagnoses in association with SARS-CoV-2 infection. The goodness of fit of the Poisson regression models was assessed by deviance chi-squared tests and overdispersion tests, which were conducted during the revision following referees’ comments [ 55 ].…”

Section: Methodsmentioning

confidence: 99%

Adverse events of special interest and mortality following vaccination with mRNA (BNT162b2) and inactivated (CoronaVac) SARS-CoV-2 vaccines in Hong Kong: A retrospective study

et al. 2022

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Background Safety monitoring of coronavirus disease 2019 (COVID-19) vaccines is crucial during mass vaccination rollout to inform the choice of vaccines and reduce vaccine hesitancy. Considering the scant evidence directly comparing the safety profiles of mRNA and inactivated SARS-CoV-2 vaccines, this territory-wide cohort study aims to compare the incidence of various adverse events of special interest (AESIs) and all-cause mortality between CoronaVac (inactivated vaccine) and BNT162b2 (mRNA-based vaccine). Our results can help vaccine recipients make an informed choice. Methods and findings A retrospective, population-based cohort of individuals who had received at least 1 dose of BNT162b2 or CoronaVac from 23 February to 9 September 2021 in Hong Kong, and had data linkage to the electronic medical records of the Hong Kong Hospital Authority, were included. Those who had received mixed doses were excluded. Individuals were observed from the date of vaccination (first or second dose) until mortality, second dose vaccination (for first dose analysis), 21 days after vaccination, or 30 September 2021, whichever came first. Baseline characteristics of vaccinated individuals were balanced between groups using propensity score weighting. Outcome events were AESIs and all-cause mortality recorded during 21 days of post-vaccination follow-up after each dose, except anaphylaxis, for which the observation period was restricted to 2 days after each dose. Incidence rate ratios (IRRs) of AESIs and mortality comparing between CoronaVac and BNT162b2 recipients were estimated after each dose using Poisson regression models. Among 2,333,379 vaccinated individuals aged 18 years or above, the first dose analysis included 1,308,820 BNT162b2 and 955,859 CoronaVac recipients, while the second dose analysis included 1,116,677 and 821,560 individuals, respectively. The most frequently reported AESI among CoronaVac and BNT162b2 recipients was thromboembolism (first dose: 431 and 290 per 100,000 person-years; second dose: 385 and 266 per 100,000 person-years). After the first dose, incidence rates of overall AESIs (IRR = 0.98, 95% CI 0.89–1.08, p = 0.703) and mortality (IRR = 0.96, 95% CI 0.63–1.48, p = 0.868) associated with CoronaVac were generally comparable to those for BNT162b2, except for Bell palsy (IRR = 1.95, 95% CI 1.12–3.41, p = 0.018), anaphylaxis (IRR = 0.34, 95% CI 0.14–0.79, p = 0.012), and sleeping disturbance or disorder (IRR = 0.66, 95% CI 0.49–0.89, p = 0.006). After the second dose, incidence rates of overall AESIs (IRR = 0.97, 95% CI 0.87–1.08, p = 0.545) and mortality (IRR = 0.85, 95% CI 0.51–1.40, p = 0.516) were comparable between CoronaVac and BNT162b2 recipients, with no significant differences observed for specific AESIs. The main limitations of this study include residual confounding due to its observational nature, and the possibility of its being underpowered for some AESIs with very low observed incidences. Conclusions In this study, we observed that the incidences of AESIs (cumulative incidence rate of 0.06%–0.09%) and mortality following the first and second doses of CoronaVac and BNT162b2 vaccination were very low. The safety profiles of the vaccines were generally comparable, except for a significantly higher incidence rate of Bell palsy, but lower incidence rates of anaphylaxis and sleeping disturbance or disorder, following first dose CoronaVac versus BNT162b2 vaccination. Our results could help inform the choice of inactivated COVID-19 vaccines, mainly administered in low- and middle-income countries with large populations, in comparison to the safety of mRNA vaccines. Long-term surveillance on the safety profile of COVID-19 vaccines should continue.

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Overdisp: A Stata (and Mata) Package for Direct Detection of Overdispersion in Poisson and Negative Binomial Regression Models

Cited by 18 publications

References 10 publications

Household livelihood diversification in rural Africa

Household livelihood diversification in rural Africa

Determinants of maternal healthcare-seeking behaviours in Ghana

Adverse events of special interest and mortality following vaccination with mRNA (BNT162b2) and inactivated (CoronaVac) SARS-CoV-2 vaccines in Hong Kong: A retrospective study

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