How can I tell if it really works or not?

To determine whether something 'really works,' follow this detailed, context-driven approach. First, clarify its purpose and define success criteria. For technical tools (e.g., software), measure performance against a baseline using A/B testing, stress testing, and success metrics like throughput (tokens/second), cost (GPU-hours/dollar), and output quality (perplexity, BLEU/ROUGE). For health or fitness regimens, focus on quantitative tracking (e.g., weight, blood pressure) over realistic timeframes and avoid placebo effects by isolating variables. For strategies or habits, monitor sustainable trends, friction reduction, and gather external feedback. Regardless of context, avoid purely anecdotal evidence, invert effort-to-reward ratios, and inconsistent results. Use controlled environments, run comparative tests, and analyze results statistically to ensure reliability. Document findings comprehensively, highlighting trade-offs and thresholds for success (e.g., ≥2× TPS, ≤0.5× cost, ≥90% schema compliance). For multimodal tools, assess cross-modal consistency via CLIP similarity or human judgment. This structured framework ensures objective evaluation tailored to the specific context of 'it.'