Instruction: Discuss how you would set up an observational study to evaluate whether implementing flexible work hours causally affects team productivity. Include methods to address potential confounders.
Context: This question assesses the candidate's ability to handle complexities in causal inference when randomized controlled trials are not feasible. The candidate should demonstrate understanding of techniques to control for confounding variables and propose a methodologically sound approach to estimate the real causal effect of flexible work hours on productivity.