### When should we use the term "nonresponse bias"?

Maybe I'm just being cranky, but I'm starting to think we need to be more careful about when we use the term "nonresponse bias." It's a simple term, right? What could be wrong here?

The situation that I'm thinking about is when we are comparing responders and nonresponders on characteristics that are known for everyone. This is a common technique. It's a good idea. Everyone should do this to evaluate the quality of the data.

My issue is when we start to describe the differences between responders and nonresponders on these characteristics as "nonresponse bias." These differences are really proxies for nonresponse bias. We know the value for every case, so there isn't any nonresponse bias.

The danger, as I see it, is that naive readers could miss that distinction. And I think it is an important distinction. If I say "I have found a method that reduces nonresponse bias," what will some folks hear? I think such a statement is probably too strong when I'm talking about differences between responders and nonresponders on known characteristics.

On the other hand, I was talking with some folks about this a couple of weeks ago. No one agreed with me on this point.

1. I agree with you, especially when it comes to the idea that some laymen (or naive readers, as you put it) might have when something like that is said. It does sound like something that probably it isn't. I, myself, have the same problem with the usage of the term "representative" to describe a sample. But maybe I'm being too puristic...

### "Responsive Design" and "Adaptive Design"

My dissertation was entitled "Adaptive Survey Design to Reduce Nonresponse Bias." I had been working for several years on "responsive designs" before that. As I was preparing my dissertation, I really saw "adaptive" design as a subset of responsive design.

Since then, I've seen both terms used in different places. As both terms are relatively new, there is likely to be confusion about the meanings. I thought I might offer my understanding of the terms, for what it's worth.

The term "responsive design" was developed by Groves and Heeringa (2006). They coined the term, so I think their definition is the one that should be used. They defined "responsive design" in the following way:

1. Preidentify a set of design features that affect cost and error tradeoffs.
2. Identify indicators for these costs and errors. Monitor these during data collection.
3. Alter the design features based on pre-identified decision rules based on the indi…

### An Experimental Adaptive Contact Strategy

I'm running an experiment on contact methods in a telephone survey. I'm going to present the results of the experiment at the FCSM conference in November. Here's the basic idea.

Multi-level models are fit daily with the household being a grouping factor. The models provide household-specific estimates of the probability of contact for each of four call windows. The predictor variables in this model are the geographic context variables available for an RDD sample.

Let $\mathbf{X_{ij}}$ denote a $k_j \times 1$ vector of demographic variables for the $i^{th}$ person and $j^{th}$ call. The data records are calls. There may be zero, one, or multiple calls to household in each window. The outcome variable is an indicator for whether contact was achieved on the call. This contact indicator is denoted $R_{ijl}$ for the $i^{th}$ person on the $j^{th}$ call to the $l^{th}$ window. Then for each of the four call windows denoted $l$, a separate model is fit where each household is assum…

### Future of Responsive and Adaptive Design

A special issue of the Journal of Official Statistics on responsive and adaptive design recently appeared. I was an associate editor for the issue and helped draft an editorial that raised issues for future research in this area. The last chapter of our book on Adaptive Survey Design also defines a set of questions that may be of issue.

I think one of the more important areas of research is to identify targeted design strategies. This differs from current procedures that often sequence the same protocol across all cases. For example, everyone gets web, then those who haven't responded to  web get mail. The targeted approach, on the other hand, would find a subgroup amenable to web and another amenable to mail.

This is a difficult task as most design features have been explored with respect to the entire population, but we know less about subgroups. Further, we often have very little information with which to define these groups. We may not even have basic household or person chara…