There are several reliable methods to measure the efficacy of an outreach strategy:

1. Analyze Engagement: One of the most immediate ways to gauge efficacy is to assess the level of engagement resulting from the campaign. This could involve monitoring likes, shares, comments, or followers.

2. Use UTM Parameters: By using UTM parameters in your campaign URLs, you can track the performance and analyze how much traffic is being directed from the influencers’ platforms.

3. Review Conversion Rates: Keep an eye on the conversion rates from the campaign. This will give you a direct vision of how the campaign is contributing to your broader objectives, such as sales or downloads.

4. Monitor Brand Mentions: You can use tools to monitor brand mentions and sentiment across various platforms. The increase in these metrics can provide a measure of its impact.

5. Evaluate Audience Growth: A successful campaign might result in a significant increase in your brand’s following on social media platforms.

6. ROI Measurement: Ultimately, all the metrics have to exhibit a positive return on investment. Comparing the cost of the campaign to the benefits accrued will offer a clear indication of the campaign’s success.

Some influencer marketing platforms, like Flinque, provide comprehensive analytics, including audience analytics, reach and engagement statistics, and ROI measurement. The tools and metrics available depend on the specific platform and its features, so brands and agencies will want to carefully select an influencer marketing platform that aligns best with their campaign objectives and measurement needs.