Related Experiment Video
Updated: Nov 11, 2025

A Method of Trigonometric Modelling of Seasonal Variation Demonstrated with Multiple Sclerosis Relapse Data
Published on: December 9, 2015
Interrupted time series analysis using autoregressive integrated moving average (ARIMA) models: a guide for
Andrea L Schaffer1, Timothy A Dobbins2, Sallie-Anne Pearson3,4
1Centre for Big Data Research in Health, UNSW Sydney, Level 2, AGSM Building, Sydney, Australia. andrea.schaffer@unsw.edu.au.
This article provides a comprehensive guide on using Autoregressive Integrated Moving Average (ARIMA) models to assess the effectiveness of large-scale health policies. It explains how these statistical tools handle complex data patterns like seasonal changes and historical trends that simpler methods often miss. The authors demonstrate this approach by analyzing a government policy aimed at reducing the inappropriate use of a specific antipsychotic medication. By offering practical steps for model selection and software code, the paper helps researchers accurately measure the real-world impact of public health interventions.
Area of Science:
- Biostatistics and health services research
- Interrupted time series analysis within public health policy evaluation
Background:
No prior work had fully resolved the limitations of segmented regression when evaluating public health policies characterized by complex temporal dependencies. Researchers often struggle to account for seasonality and autocorrelation in longitudinal health datasets. That uncertainty drove the need for more robust statistical frameworks capable of handling these specific data challenges. Prior research has shown that standard linear models frequently fail to capture the underlying trends inherent in large-scale population data. This gap motivated the exploration of alternative methodologies that provide greater flexibility for impact assessment. Autoregressive Integrated Moving Average models offer a sophisticated solution for addressing these recurring analytical difficulties. The current literature lacks a clear, accessible guide for applying these advanced techniques to real-world policy evaluations. This article addresses that deficiency by detailing the theoretical and practical application of these models for public health scientists.
Purpose Of The Study:
The aim of this article is to provide a comprehensive guide for using Autoregressive Integrated Moving Average models to evaluate large-scale health interventions. Researchers often encounter difficulties when applying standard segmented regression to datasets with complex temporal patterns. This study addresses the specific challenge of accounting for seasonality and autocorrelation in population-level health data. The authors seek to clarify the theoretical basis for these advanced models in the context of policy assessment. They intend to help scientists select the appropriate impact shape and model structure for their specific research questions. The paper also aims to demonstrate the practical application of these methods through a real-world case study. By providing software code, the authors hope to facilitate the adoption of these techniques by the broader scientific community. This work serves as a resource for improving the accuracy and reliability of public health policy evaluations.
Main Methods:
The review approach focuses on the theoretical foundations and practical implementation of advanced time series modeling for policy assessment. Authors synthesize guidelines for selecting appropriate model structures and defining the shape of intervention impacts. The investigation details the systematic process for identifying optimal parameters and verifying statistical fit. Researchers describe the application of transfer functions to capture the dynamic nature of public health changes. The study provides computational scripts for both R and SAS environments to support replication. A case study involving antipsychotic medication dispensing illustrates the application of these statistical procedures. The methodology emphasizes rigorous diagnostic testing to ensure the validity of the resulting impact estimates. This framework offers a structured pathway for applying complex temporal models to longitudinal health datasets.
Main Results:
Key findings from the literature demonstrate that these models effectively account for underlying trends, autocorrelation, and seasonality in health data. The authors show that this approach provides a flexible way to model various types of intervention impacts. The case study regarding the 2014 Australian policy change successfully illustrates the practical application of these techniques. Results indicate that the removal of prescription refills for 25 mg quetiapine tablets can be analyzed using these sophisticated statistical methods. The authors report that the model selection process is a critical step in achieving accurate evaluations. Their synthesis confirms that these models outperform simpler regression when data exhibit complex temporal patterns. The findings highlight the utility of transfer functions in capturing the specific nature of policy effects. The analysis confirms that these methods provide a robust alternative for evaluating large-scale health interventions.
Conclusions:
The authors propose that Autoregressive Integrated Moving Average models serve as a versatile instrument for assessing population-level health changes. This synthesis suggests that these models effectively manage complex temporal patterns that simpler regression techniques often overlook. The researchers emphasize that selecting the appropriate impact shape remains a primary requirement for accurate policy evaluation. Their review indicates that transfer functions provide a flexible mechanism for modeling diverse intervention effects over time. The authors conclude that incorporating diagnostic checks ensures the reliability of the final statistical interpretation. They suggest that the provided software scripts facilitate the adoption of these methods by the broader research community. The study highlights that accounting for autocorrelation and seasonality is necessary for valid causal inference in health policy research. These findings imply that advanced time series approaches are superior for evaluating interventions when standard methods prove inadequate.
Frequently Asked Questions
The researchers propose that these models utilize transfer functions to capture the specific shape of an intervention's effect. Unlike simpler regression, this approach accounts for autocorrelation and seasonality, which are common in population-level dispensing data.
The authors provide R and SAS code to assist investigators in replicating their results. These scripts guide users through the model selection process, diagnostic checking, and the interpretation of findings for various policy scenarios.
The researchers state that this method is necessary when data exhibit complex temporal dependencies, such as seasonal fluctuations or historical trends. Standard segmented regression often fails to produce valid results in these specific conditions.
Dispensing claims data serve as the primary input for evaluating the policy. This information allows for the longitudinal tracking of medication usage before and after the government intervention.
The authors illustrate the model using the 2014 Australian government policy that removed prescription refills for 25 mg quetiapine tablets. This case study demonstrates how to measure the impact of policies aimed at reducing inappropriate drug use.
The researchers claim that this approach allows for flexible modeling of different impact types. They suggest that this capability makes it a superior tool for evaluating large-scale interventions compared to traditional regression methods.
More Related Videos
Related Concept Videos
Introduction To Survival Analysis
The primary goal of survival analysis is to estimate survival time—the time...
Steps in Outbreak Investigation
Statistical Methods for Analyzing Epidemiological Data
Comparing the Survival Analysis of Two or More Groups
Mechanistic Models: Compartment Models in Individual and Population Analysis
Analysis of Population Pharmacokinetic Data

