Nonrandomized sample size and confounding

Plan precision adjustment and overlap

Information planning must reflect the proposed estimator, imbalance, clustering and attrition. Increasing sample size narrows random error but does not eliminate selection bias or residual confounding.

Flow diagram

Steps

Define primary contrast

Specify estimand, outcome distribution and intended interpretation.

Identify confounding structure

Select adjustment factors using causal knowledge and assignment mechanisms.

Assess overlap and effective information

Anticipate unequal groups, weighting losses and clustering.

Plan precision or power scenarios

Document effect, variation, attrition and adjustment assumptions.

Plan diagnostics and residual-bias sensitivity

Record balance, support and sensitivity to unmeasured factors.