Marketers use metrics to measure the effectiveness of social media marketing strategies by comparing results to specific objectives. Common metrics include reach, frequency, site stickiness, clickthroughs, sales conversions, and viewthroughs. Engagement metrics provide information about the quality of interactions with a brand rather than just the quantity. The DATA approach involves defining goals, assessing costs and potential value, tracking actual results, and adjusting strategies based on results. Calculating social media ROI requires assigning financial values to inputs and outcomes to measure profitability. Both direct and indirect benefits must be considered when assessing social media programs.