Experimental Design
Experimental Design Structure
1. Type of Study and Allocation Framework:
This study is structured as a prospective, longitudinal, individual-level randomized controlled trial (RCT) spanning 24 weeks (6 months) from July to December 2026. Randomization will be executed with a 1:1:1 allocation ratio across three independent experimental arms: Arm A (Manual Management / Control), Arm B (Hybrid/Nudge Treatment), and Arm C (Fully Automated Management / Treatment).
2. Randomization Strategy:
Randomization will occur at the individual level immediately following the baseline data collection (T0). To ensure covariate balance across the experimental arms, we will implement a stratified block randomization strategy. The stratification factors are baseline age cohorts and educational attainment levels, which are critical predictors of financial literacy and digital interface adoption. The randomization sequence will be generated via a computer algorithm in RStudio, ensuring full concealment from both the participants and the field researchers until the moment of assignment.
3. Sample Size, Power Analysis, and Attrition Target:
Based on an a priori power calculation for longitudinal panel models, we established a target power of 80% (1 - Beta = 0.80), a significance level of 5% (Alpha = 0.05), and a Minimum Detectable Effect Size (MDES) of f^2 = 0.15. The statistical power framework requires a minimum of 160 active participants per experimental arm, equating to 480 effective subjects. To aggressively safeguard against potential panel attrition, the trial will recruit an initial sample size of N = 750 participants. This structure absorbs a projected 30% attrition rate over the 6-month timeline while retaining approximately 500 final effective participants, comfortably exceeding the power threshold. Furthermore, the high-frequency measurement design (48 total points per individual via twice-weekly Experience Sampling Method prompts) drastically enhances intra-individual precision and statistical power.
4. Econometric and Analytical Strategy:
The public data analysis plan relies on three highly parsimonious and complementary analytical frameworks to evaluate the temporal dynamics of the intervention:
* Fixed-Effects (FE) Panel Models: Used as the primary econometric strategy to control for time-invariant unobserved individual heterogeneity, isolating the clean causal impact of automated nudging over time.
* Latent Growth Curve Models (LGM): Deployed to parametrically model and map the individual and aggregate longitudinal trajectories of financial agency and resilience across the 24-week period, integrating the exogenous price shocks as time-dependent predictors.
* Causal Forest (Machine Learning Causal Inference): Utilized to optimize the estimation of Conditional Average Treatment Effects (CATE). This approach will systematically uncover treatment effect heterogeneity and identify specific vulnerable socio-economic or cognitive subgroups without risking arbitrary post-hoc specification mining.
Other complex structural or multi-group extensions, such as Structural Equation Modeling (SEM) for latent construct validation, will be restricted strictly to secondary verification to preserve model parsimony. Non-random attrition patterns will be verified using the Verbeek-Nijman test, complemented by Inverse Probability Weighting (IPW) adjustments if necessary. Potential extreme data volatility in behavioral latencies or expenditure entries will be managed using systematic winsorizing at the 1% and 99% thresholds.