Analysis of count event data such as mortality cases, were often modelled using Poisson regression model. Maximum likelihood procedures were used by using SAS software to estimate the model parameters of a Poisson regression model. However, the Negative Binomial distribution has been widely suggested as the alternative to the Poisson when there is proof of overdispersion phenomenon. We modelled the mortality cases as the dependent variable using Poisson and Negative Binomial regression and compare both of the models. The procedures were done in SAS by using the function PROC GENMOD. The results showed that the mortality data in Poisson regression exhibit large ratio values between deviance to degree of freedom which indicate model misspecification or overdispersion. This large ratio was found to be reduced in Negative Binomial regression. The Normal probability plot of Pearson residual confirmed that the Negative Binomial regression is a better model than Poisson regression in modelling the mortality data. The objective of this study is to compare the goodness of fit of Poisson regression model and Negative Binomial regression model in the application of air pollution epidemiologic time series study by using SAS software.

Introduction: Acne is the most common skin disease among adolescents and has significant psychological distress. Our objective is to assess acne severity, functional disability, and its psychological distress among acne patients. Methods: A cross-sectional study was conducted from November 2021 to May 2022 among 163 acne patients attending Dermatology Clinics in the district of Kuantan, Pahang. The severity of acne was graded using the Comprehensive Acne Severity Scale (CASS). The functional disability index was measured using a Cardiff Acne Disability Index (CADI), while Depression, Anxiety and Stress Scale (DASS-21) questionnaires were used as a screening tool to detect the psychological distress of acne. Data were analysed using a Chi-square test, Fisher’s exact test and multiple logistic regression. Results: The mean age was 23 years, 60.1% were female, 94.5% were Malay, and 68.1% were unemployed. The severity of acne was more prominent in the mild (30.7%) and moderate (28.2%) categories. A total of 20.2%, 11.7%, and 4.9% of the respondents had anxiety, depression, and stress symptoms, respectively. Regarding the respondents’ functional disability, 40.5% had mild impairment, 38.0% had moderate impairment, and 13.5% had severe impairment. Acne severity was found to be significantly associated with the functional disability index (P<0.05). The functional disability index was also found to be significantly associated with depression (p=0.019) and anxiety symptoms (p=0.042). Conclusion: Clinical management of acne patients should include not only pharmacological treatment but also consideration of the disease’s functional disability status and psychological distress.