Sanity-check survey weights

Inputs: [WEIGHT VALUES], [SAMPLE SUMMARY], [TARGET TOTALS]. Inspect supplied row-level weights for missing, zero and extreme values; calculate effective sample size only if the necessary weights are available. Compare documented target margins where the data permit. Output: A diagnostics table, limits and questions for the survey designer. Check: Weighted totals match documented targets or differences are explained; never manufacture row-level diagnostics from a summary alone. State whether the effective sample size formula fits the survey design before interpreting it.