### Mired in Myopia?

Reinforcement Learning (RL) deals with multi-step decision processes. One strategy for making decisions in a multi-step environment is always choose the option that maximizes your immediate payoff. In RL, they call this strategy "myopic" since it never looks beyond the payoff for the current action.

The problem is that this strategy might produce a smaller total payoff at the end of the process. If we look at the process as a whole, we may identify a sequence of actions that produces a higher overall reward while not maximizing the reward for each individual action.

This all relates to an experiment that I'm running on contact strategies. The experiment controls all calls other than appointments and refusal conversion attempts. The overall contact rate was 11.6% for the experimental protocol, and 9.0% for the control group. The difference is statistically significant.

But establishing contact is only an intermediate outcome. The final outcome of this multi-step process is completing an interview. It appears that the control and experimental groups produce interviews at about the same rate (147 control vs 153 experiment). Timestamps on the call indicate that the experimental contact strategy reduces time spent achieving the first contact by about 10%, but overall savings are only about 2% (i.e. not really different).

This looks like a case where a myopic policy (i.e. improving only the contact stage) does not lead to overall gains. The current experimental protocol will need to be expanded to all stages somehow. That's a big step...

### "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…

### Is there such a thing as "mode"?

Ok. The title is a provocative question. But it's one that I've been thinking about recently. A few years ago, I was working on a lit review for a mixed-mode experiment that we had done. I found that the results were inconsistent on an important aspect of mixed-mode studies -- the sequence of modes.

As I was puzzled about this, I went back and tried to write down more information about the design of each of the experiments that I was reviewing. I started to notice a pattern. Many mixed-mode surveys offered "more" of the first mode. For example, in a web-mail study, there might be 3 mailings with the mail survey and one mailed request for a web survey. This led me to think of "dosage" as an important attribute of mixed-mode surveys.

I'm starting to think there is much more to it than that. The context matters  a lot -- the dosage of the mode, what it may require to complete that mode, the survey population, etc. All of these things matter.

Still, we ofte…