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The objective of population modeling is to study the impact of tobacco products on the population as whole. Input parameters include demographic information, tobacco use transition probability, and mortality and/or morbidity. The input Input parameters are typically derived from population-level sources (e.g., census data or other population-level surveys). However, depending on the objective, other sources of data may be used. When using these other sources, steps should be taken

Input parameters are an important component of model development, verification, and validation. In many population models in a tobacco research setting, input parameters are used to incorporate tobacco use behaviors and risks that occur under scenarios of interest—for example, models to evaluate the health impact associated with introducing a new tobacco or policy that may result in product switching, dual use, or polytobacco use. Input parameters may be obtained from a variety of data sources, and depending on the objectives of the model, they may include population surveys representative of the population of interest (e.g., population distribution, birth rates, migration rates, death/other morbidity rates, tobacco product use behavior prevalence). This section provides a characterization of several classes input parameters informative in developing the TIG.  

In this section, the inputs to these models and how they are represented in CDISC standards for submission to a regulatory authority are discussed. “Model Model outputs are not currently covered in this section but may be covered in a later release. ” However, regulatory agencies expect full information to replicate the analysis based in the outputs.

Transition into discussion of examples - to be discussed:

Selection of initial model input parameters is an important step during model development. Input parameters are typically chosen to represent characteristics of the entire population: transitional probabilities (initiation, cessation, quitting, switching) and health outcome (mortality and/or morbidity rates). The initial values of these parameters are typically estimated from sources representative of the population, such complex probability population survey and census. 

Examples

Initial Population

• demographics (age, gender, and race)
• birth rate "if open system"
• morbidity/mortality 
• initial tobacco prevalence
• immigration rates "If open system"

Transition probabilities/rates for initial population

• initial population (file) - describing states of tobacco use covered by the model
• transition probability (file)

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