Let’s have a look at online sample routers
The problem of router bias

Respondents in routers

The heart of routing is screening respondents. Conceptually, routing involves amassing all of the screening questions of waiting surveys (of which there typically are hundreds) and packaging them in a way that they can be efficiently administered while minimizing the chances that a respondent gets routed to a survey and then fails to qualify.  Some companies also use whatever information they already have on an individual to shorten the screening time. This might include profiling information on their panel members or, for non-panel members, information stored from a previous visit to the router by that individual.

One obMazevious concern is the fate of potential respondents in this process. Some people may take a long time to qualify and sometimes a respondent can pass the screener but still don't qualify in the survey proper. It's not uncommon to offer screen-outs, and occasionally completes, the opportunity go back into the router to try to qualify for another survey. Some companies place limits on how long they will let a person be in the router. Others limit the number of survey opportunities offered while some take the attitude that it's the Internet and people will do what people will do. Unlike real black holes, people can and do escape.

There are some major differences in the way all of this is managed. Going into the ARF meeting I thought I understood that there are three main types of router designs:

  1. Serial routers in which screening questions for waiting surveys are asked one after the other until a respondent qualifies. These routers generally are smart enough to remember questions in common across the waiting surveys so that a specific question only gets asked once of each respondent.
  2. Parallel routers in which a randomized set of screening questions is asked and then a respondent is routed to a survey for which he or she qualifies. This assignment might be random or it might be based on an algorithm that considers the needs of all waiting surveys.
  3. Hierarchical routers which start with a main router where a few basic questions are asked and then people are passed to one of several mini-routers that feed surveys with similar qualifiers, on similar topics, etc.

In practice it's nowhere near that clean. Most companies seem to use a mix of hierarchical and serial routing. And everyone has arguments about why their approach is best.

In my next post I'll describe the problem that everyone worries about: router bias.