The idea of a construct map is a more precise concept than construct. We assume that the construct we wish to measure has a particularly simple form—it extends from one extreme to another, from high to low; small to large, positive to negative, or strong to weak. There may be some complexity in what happens in between these extremes, but we are primarily interested in where a respondent stands on this range from one extreme to the other. In particular, there may be distinguishable qualitative levels between the extremes—these are important and useful in interpretation. At this point, it is still an idea, latent rather than manifest. Although qualitative levels are definable, we assume that the respondents can be at any point in between— that is, the underlying construct is continuous. In summary, a construct map can be said to be a unidimcnsional latent variable. Many constructs are more complex than this. For example, they may be multidimensional. This is not a barrier to the use of the methods described in this book—the most straightforward thing to do is tackle each dimension one at a time—that way they can each be seen as a construct map. There are also constructs that are quite different from those that can be well described by a construct map. For example, suppose the construct consists of two different groups, say those who are likely to immigrate and those who are not. This construct is not much like that of a construct map and, hence, is not likely to be well represented by one.