Quest Journals
Journal of Research in Applied Mathematics
Volume 3 ~ Issue 5 (2017) pp: 01-10
ISSN(Online) : 2394-0743 ISSN (Print): 2394-0735
www.questjournals.org
*Corresponding Author: Neha Jain 1 | Page
Rahul Gupta Department of Statistics, University Of Jammu, Jammu, J and K, India
Research Paper
Generalized Additive and Generalized Linear Modeling for
Children Diseases
Neha Jain, Roohi Gupta and Rahul Gupta*
Rahul Gupta Department of Statistics, University Of Jammu, Jammu, J and K, India
Received 03 Feb, 2017; Accepted 18 Feb, 2017 © The author(s) 2017. Published with open access at
www.questjournals.org
ABSTRACT: This paper is necessarily restricted to application of Generalised Linear Models(GLM) and
Generalised Additive Models(GAM), and is intended to provide readers with some measure of the power of
these mathematical tools for modeling Health/Illness data systems. We are all aware that illness, in general
and children illness, in particular is amongst the most serious socio-economic and demographic problems in
developing countries, and they have great impact on future development. In this paper we focus on some
frequently occurring diseases among children under fourteen years of age, using data collected from various
hospitals of Jammu district from 2011 to 2016.The success of any policy or health care intervention depends on
a correct understanding of the socio economic environmental and cultural factors that determine the occurrence
of diseases and deaths. Until recently, any morbidity information available was derived from clinics and
hospitals. Information on the incidence of diseases, obtained from hospitals represents only a small proportion
of the illness, because many cases do not seek medical attention .Thus, the hospital records may not be
appropriate from estimating the incidence of diseases from programme developments. The use of DHS data in
the understanding of the childhood morbidity has expanded rapidly in recent years. However, few attempts have
been made to address explicitly the problems of non linear effects on metric covariates in the interpretation of
results .This study shows how the GAM model can be adapted to extent the analysis of GLM to provide an
explanation of non linear relationship of the covariate. Incorporation of non linear terms in the model improves
the estimates in the terms of goodness of fit. The GLM model is explicitly specified by giving symbolic
description of the linear predictor and a description of the error distribution and the GAM model is fit using the
local scoring algorithm, which iteratively fits weighted additive models by back fitting. The back fitting
algorithm is a Gauss-Seidel method of fitting additive models by the iteratively smoothing partial residuals. The
algorithm separates the parametric from the non parametric parts of the fit, and fits the parametric part using
weighted linear least squares within the back fitting algorithm.
Keywords: Generlised additive model, Generalised linear model, weighted linear least squares
I. INTRODUCTION
Generalized additive model (GAM) is a generalized linear model in which the linear predictor depends
linearly on unknown smooth functions of some predictor variables, and interest focuses on inference about these
smooth functions. GAMs were originally developed by Trevor Hastie and Robert Tibshirani to blend properties
of generalized linear models with additive models. Generalized linear model (GLM) is a flexible generalization
of ordinary linear regression that allows for response variables that have error distribution models other than
a normal distribution. The GLM generalizes linear regression by allowing the linear model to be related to the
response variable via a link function and by allowing the magnitude of the variance of each measurement to be a
function of its predicted value.Generalized linear models were formulated by John Nelder and Robert
Wedderburn as a way of unifying various other statistical models, including linear regression , logistic
regression and Poisson regression . They proposed an iteratively reweighted least squares method for maximum
likelihood estimation of the model parameters. Maximum-likelihood estimation remains popular and is the
default method on many statistical computing packages. Other approaches, including Bayesian approaches
and least squares fits to variance stabilized responses, have been developed. Significant statistical development
in the last three decades has been the advances in regression analysis provided by generalized additive models
(GAM) and generalized linear models (GLM).These three alphabet acronyms translate into a great scope for
application in many areas of applied scientific research. Based on developments by Cox and Snell[1] in the late
sixties, the first seminal publications, also providing the link with practice (through software availability), were