Modeling Event Count data with Proc GENMOD and the SAS System
نویسنده
چکیده
Event count data are distinguished by being positive and integer valued with often small numbers of unique values. Examples include just about anything measured by counts or summary frequency data. Standard ordinary least squares (OLS) regression modeling requires the assumption that the model errors, εi, are independently and identically distributed, (i.i.d.)~ N(0,σ), normal random variables. In practice, however, departures from this ideal situation are common. This broader class of regression models can be handled under a powerful and flexible set of models called General Linear Models, or GLMs, see McCullagh and Nelder (1989) .
منابع مشابه
Model Fitting in PROC GENMOD
There are several procedures in the SAS System for statistical modeling. Most statisticians who use the SAS system are familiar with procedures such as PROC REG and PROC GLM for fitting general linear models. However PROC GENMOD can handle these general linear models as well as more complex ones such as logistic models, loglinear models or models for count data. In addition, the main advantage ...
متن کامل184-31: Fixed Effects Regression Methods in SAS®
Fixed effects regression methods are used to analyze longitudinal data with repeated measures on both independent and dependent variables. They have the attractive feature of controlling for all stable characteristics of the individuals, whether measured or not. This is accomplished by using only within-individual variation to estimate the regression coefficients. This paper surveys the wide va...
متن کاملWhy We Need an R Measure of Fit (and Not Only One) in Proc Logistic and Proc Genmod
We propose to use two seemingly different R measures of fit in PROC LOGISTIC and PROC GENMOD (SAS/STAT), and we show that they are closely related to each other in terms of the amount of information gained when including predictors, in comparison with the “null” model. We suggest working with these R measures simultaneously rather than separately because they can be seen as two faces of the sam...
متن کامل164-2013: Using PROC GENMOD to Investigate Drug Interactions: Beta Blockers and Beta Agonists and Their Effect on Hospital Admissions
Every year, more than half a million adverse reactions to drugs are reported to the FDA. This paper is a real-world, large-scale review of beta blockers and beta agonist usage. We use New York City public hospitals’ records to investigate whether interactions of beta blockers and beta agonists are associated with increased hospital inpatient admissions, a common indicator of health care quality...
متن کاملSUGI 28: Estimation of Prevalence Ratios When PROC GENMOD Does Not Converge
When studying a prevalent outcome, it is often of interest to estimate the prevalence ratio instead of the odds ratio. In SAS one can use PROC GENMOD with the binomial distribution and the log link function. Unlike the logistic model, the log-binomial model places restrictions on the parameter space, and the maximum likelihood estimate (MLE) might occur on the boundary of the parameter space, i...
متن کامل