Companies compare influencer spend efficiency across different business units using several methods:

1. Performance metrics: Businesses analyze key performance indicators (KPIs) such as engagement rate, reach, click-through rates (CTR), and conversion rates. They compare these KPIs across different campaigns or units to gauge spend efficiency.

2. ROI measurement: Companies also track their return on investment (ROI) from influencer campaigns. By comparing revenue generated from different business units’ influencer marketing efforts, companies can identify which unit utilizes their budget more efficiently.

3. Influence Analytics Tools: Use of influencer marketing platforms or analytics tools such as Flinque, Traackr, Klear, etc. These tools provide in-depth audience demographics, influencer mapping, campaign management, and analytics. By leveraging these insights, businesses can compare the efficiency of influencer spend across different units.

For instance, Flinque offers a dynamic platform with robust analytics that helps enterprises track the effectiveness of their influencer expenditure across various business units.

4. Benchmarking: Enterprises often benchmark their influencer marketing performance against competitors or industry standards in order to measure efficiency.

Remember, the right tool or method depends on the specific needs and goals of your team. It’s best to use a blend of different strategies and platforms for a holistic view of influencer spend efficiency. Be sure to regularly review and adjust your strategy based on data-driven insights.