15.6 Selecting the best tool

Task	Often suitable	Reason
Reproducible cleaning and modelling	R	Saved code, packages, validation, automation
Client-editable assumption model	Excel	Familiar review and transparent cell calculations
Interactive recurring reporting	Power BI	Data model, measures, filters, refreshable pages
Data dictionary and source log	Excel	Filterable structured tables and collaborative review
Final narrative report	Bookdown or document system	Integrated prose, figures, references, and appendices

The best tool is the one that supports correctness, auditability, audience use, and maintenance for the task. Using several tools is reasonable when handoffs and definitions are controlled.

Common mistake: Recreating the same calculation independently in R, Excel, and Power BI without a reconciliation plan can produce three plausible but inconsistent answers.