Recovering Causal Effects with Sequential Adjustment for Confounding and Attrition

מושגי ליבה

The authors introduce the sequential adjustment criteria (SAC) to recover causal effects in the presence of confounding and attrition bias. They also propose a targeted sequential regression (TSR) estimator that is multiply robust under certain conditions.

תקציר

The content discusses the challenges of confounding bias and selection bias, particularly in the context of informative missingness or attrition, in applied causal inference. The authors introduce the sequential adjustment criteria (SAC) as a set of graphical conditions that enable the recovery of causal effects, including the average treatment effect (ATE), even in scenarios where existing methods fall short.
Key highlights:

The SAC extends available graphical conditions for recovering causal effects using sequential regressions, allowing for the inclusion of post-exposure and forbidden variables in the admissible adjustment sets.
The authors propose the targeted sequential regression (TSR) estimator for the ATE, which is multiply robust under certain conditions. This means the estimator remains consistent if at least one of the following holds: (i) the sequential regression models are correctly specified, (ii) the exposure and selection propensity score models are correctly specified, or (iii) the exposure propensity score model and the mean-imputation model are correctly specified.
The TSR estimator capitalizes on the collective robustness conditions of regression-based, IPW-based, and imputation-based solutions, broadening the scope of scenarios where a TMLE procedure can yield a consistent estimate of a causal effect in the presence of missing data.
The authors apply the developed procedures to estimate the causal effects of pharmacological treatment for attention-deficit/hyperactivity disorder (ADHD) on the scores obtained by diagnosed Norwegian schoolchildren in national tests.

סטטיסטיקה

The authors use observational data on n = 9,352 Norwegian schoolchildren diagnosed with ADHD to estimate the causal effect of pharmacological treatment on their academic achievement scores.

ציטוטים

"Confounding bias and selection bias are two significant challenges to the validity of conclusions drawn from applied causal inference."
"We introduce the sequential adjustment criteria (SAC), which extend available graphical conditions for recovering causal effects using sequential regressions, allowing for the inclusion of post-exposure and forbidden variables in the admissible adjustment sets."
"The TSR estimator capitalizes on the collective robustness conditions of regression-based, IPW-based, and imputation-based solutions, broadening the scope of scenarios where a TMLE procedure can yield a consistent estimate of a causal effect in the presence of missing data."

תובנות מפתח מזוקקות מ:

Recovery and inference of causal effects with sequential adjustment for confounding and attrition

by Joha... ב- arxiv.org 10-01-2024

https://arxiv.org/pdf/2401.16990.pdf

שאלות מעמיקות

How can the SAC be extended to handle more complex causal structures, such as those involving time-varying confounding or dynamic treatment regimes?

The Sequential Adjustment Criteria (SAC) can be extended to accommodate more complex causal structures by incorporating additional layers of temporal dynamics and treatment variations. In scenarios involving time-varying confounding, the SAC can be adapted by allowing for the inclusion of covariates that change over time, thus enabling the identification of appropriate adjustment sets that account for the evolving nature of confounding variables. This can be achieved by defining a framework that explicitly models the temporal relationships between exposure, outcome, and confounders, potentially using time-indexed directed acyclic graphs (DAGs) or structural causal models (SCMs) that reflect these dynamics.
For dynamic treatment regimes, where treatment assignment may depend on previous outcomes or covariates, the SAC can be modified to include sequential decision-making processes. This involves specifying a set of rules or algorithms that dictate how treatments are assigned based on prior observations, thereby allowing for the recovery of causal effects in a manner that respects the temporal ordering of events. By integrating these elements into the SAC framework, researchers can enhance its applicability to a broader range of causal inference problems, ensuring that the criteria remain robust even in the presence of complex interdependencies and feedback loops.

What are the potential limitations or drawbacks of the TSR estimator, and how can it be further improved or optimized?

The Targeted Sequential Regression (TSR) estimator, while robust and efficient, does have potential limitations. One significant drawback is its reliance on the correct specification of the underlying models for the expected outcomes and propensity scores. If these models are misspecified, the estimator may yield biased results, undermining its robustness. Additionally, the TSR estimator may face challenges in high-dimensional settings where the number of covariates is large relative to the sample size, leading to overfitting and instability in the estimates.
To improve and optimize the TSR estimator, several strategies can be employed. First, incorporating machine learning techniques, such as ensemble methods or regularization approaches, can enhance model flexibility and reduce the risk of overfitting. Second, implementing cross-validation techniques during the model training phase can help in selecting the best-performing models for the expected outcomes and propensity scores, thereby improving the overall accuracy of the estimates. Lastly, exploring alternative loss functions that are more robust to outliers or extreme values can further enhance the estimator's performance, particularly in real-world applications where such issues are prevalent.

How can the proposed methods be applied to other domains beyond the ADHD example, such as in social sciences, economics, or public health research?

The methods proposed in the context of the SAC and TSR estimator can be effectively applied across various domains, including social sciences, economics, and public health research. In social sciences, these methods can be utilized to analyze the causal effects of interventions, such as educational programs or policy changes, on outcomes like academic performance or social behavior. By employing the SAC, researchers can identify appropriate adjustment sets that account for confounding variables, ensuring that the causal inferences drawn are valid and reliable.
In economics, the proposed methods can be applied to evaluate the impact of economic policies or market interventions on economic outcomes, such as employment rates or income levels. The ability to handle complex causal structures, including time-varying confounding, makes these methods particularly valuable in dynamic economic environments where multiple factors influence outcomes over time.
In public health research, the SAC and TSR estimator can be instrumental in assessing the effectiveness of health interventions, such as vaccination programs or lifestyle modifications, on health outcomes. By addressing issues of confounding and attrition, these methods can provide robust estimates of causal effects, guiding evidence-based decision-making in public health policy.
Overall, the flexibility and robustness of the SAC and TSR estimator make them suitable for a wide range of applications, enabling researchers to draw meaningful causal inferences in diverse fields.