Hit Rate

In general, hit rate is a ratio or a proportion, and the term is used in many environments and disciplines with specific definitions for both the denominator and numerator. In the online world, it usually means the number of “hits” a Web page receives during some period of time. In marketing, it can mean the number of sales achieved as a percentage of the number of sales calls made. In survey research, hit rate is most commonly used to refer to the proportion of telephone numbers in a sample that are working residential numbers. However, hit rate is sometimes used to mean incidence. Both meanings of hit rate are essential components of sample size calculations.

In its common usage, hit rate is synonymous with the terms working residential rate and working phone rate. For a residential telephone sample, eligible units would be those numbers that connect to a household, while ineligible numbers would include nonworking or disconnected numbers, data/fax lines or numbers that connect to an ineligible unit such as a business. For an in-person survey it might mean the proportion of occupied housing units in the frame, and for a mail survey it could mean the proportion of deliverable mail pieces in the list.

Hit rate is also sometimes used as a surrogate for incidence or the proportion of qualified contacts to all contacts. For example, a survey might require screening households for further eligibility, such as living within a particular geography, having a certain income, or belonging to a specific racial or ethnic group. In these cases the hit rate would be the probability of finding members of that target population among all contacts.

Understanding and being able to estimate these two hit rates is integral to sample design. Most formulas for calculating the number of sample units needed to complete a set number of interviews include both of these definitions of hit rate (working phone rate and incidence) in conjunction with estimates of contact rate and completion rate for the survey.