title: Testing an extended theoretical framework to explain variance in use of a public health information system.
abstract: OBJECTIVE
  This study examined determinants of using an immunization registry, explaining the variance in use. The technology acceptance model (TAM) was extended with contextual factors (contextualized TAM) to test hypotheses about immunization registry usage. Commitment to change, perceived usefulness, perceived ease of use, job-task changes, subjective norm, computer self-efficacy and system interface characteristics were hypothesized to affect usage.
  
  
  METHODS
  The quantitative study was a prospective design of immunization registry end-users in a state in the United States. Questionnaires were administered 100 end-users after training and system usage.
  
  
  RESULTS
  The results showed that perceived usefulness, perceived ease of use, subjective norm and job-tasks change influenced usage of the immunization registry directly, while computer self-efficacy and system interface characteristics influenced usage indirectly through perceived ease of use. Perceived ease of use also influenced usage indirectly through perceived usefulness. The effect of commitment to change on immunization registry usage was insignificant.
  
  
  CONCLUSIONS
  Understanding the variables that impact information system use in the context of public health can increase the likelihood that a system will be successfully implemented and used, consequently, positively impacting the health of the public. Variables studied should be adequate to provide sufficient information about the acceptance of a specified technology by end users.
authors.forename: Victoria
authors.initials: V
authors.lastname: Wangia
keywords: Health information technology; Public health; Public health informatics; TAM, Immunization registry; Technology acceptance model