Incidence Rate

Incidence Rate (IR) is the percentage of people who respond to a research invitation that will qualify for your study based on your screening criteria.

Why It Matters

The incidence rate has direct, practical consequences for recruiting:

• High IR (e.g., 50%): Half of respondents qualify. Recruiting is relatively straightforward.
• Low IR (e.g., 10%): Only 10% qualify. For every 100 people who complete your screener, you get 10 qualified participants.

Every screening criterion you add—"must have used a competitor in the last week," "must be a parent of a toddler," "must have a specific job title"—lowers the IR further.

The Recruiting Math

If you need 10 qualified participants and your IR is 10%, you need 100 people to complete your screener. If your response rate (people who see your invitation and complete the screener) is only 5%, you need to reach 2,000 people with your invitation.

B2B Research Challenge

Incidence rate is especially challenging for B2B research. Finding "enterprise resource planning specialists" or "neurosurgeons" in the general population means near-zero incidence rates. This is why B2B research often requires specialized recruitment agencies with pre-screened professional panels.

Understanding incidence rate helps you plan realistic timelines and budgets for recruiting.