http://library.mit.edu/item/000926877
Unobtrusive measures / Eugene J. Webb
"there are the erosion measures, where the degree of selective wear on some material yields the measure. [...] On the other hand, there are accretion measures, where the research evidence is some deposit of materials. Immediately one thinks of anthropologists working with refuse piles and pottery shards. The trace measures could be further subdivided according to the number and pattern of units of evidence. We might have two subclasses: remnants, where there is only one or a few indicators of the past behavior available, and series, where the is an accumulative body of evidence with more units, possibly deposited over a longer period of time." (36)
-- powerful categories of marks: they seem to be discussing primarily non-intentional acts, but they would apply equally well to intentional aspects of artwork

"physical evidence is, for the most part, free of reactive measurement effects" (50)
-- that is, since people generally ignore its presence, they usually do not think to falsify it.

"With accretion measures, there is the question of whether the materials have selectively survived or been selectively deposited." (50) In other words, whether they are "durable artifacts." (Naroll 1956)

Among other discussions, Webb et al. point to the various effects of social activation through time on the physical surroundings, giving example inference studies. These inferences rely on a foreknowledge of the type of interactions that could take place between the individual participants and the material objects of record.

For instance, in assuming that the erosion rate in the tiles around various museum exhibits is a rough indicator of the popularity of the respective exhibits, we make the assumption of a very limited set of events that affect erosion rate. If there were unknown water damage, or someone who wanted to frustrate the data and eroded ground around certain exhibits, the data gathered would be inaccurate. Critically, there is a major assumption being made: that we can comprehend and enumerate the set of possible effects that can occur to this material object.

If we cannot, or do not, then we can be deceived. Falsification of otherwise innocuous effects of social erosion and accretion provides a fascinating set of possible projects in this realm.

They also discuss methods of simple observation: "exterior physical signs, expressive movement, physical location, language behavior (conversational sampling), and time duration. [...] they are 'simple' only in that the investigator does not intervene in the production of the material." (116)
-- clearly, this is the position of a witness to non-participatory artistic practice: when we speak of interpretation of a work, we are alluding at first to the interior experience of it. When we attempt to clarify and elucidate that experience, we are almost invariably reduced to the kinds of observational discussions Webb &al consider here.

regarding time duration: "The amount of attention paid by a person to an object has long been the source of inferences on interest. [...] the longer the time, the greater the interest" (134-5)
-- why is this only accurate when directed by a person->object? seems to work just as well for attention paid by society: ie, in measuring the interest of a society in a given work of art (see citation web, Stefaner 2009, etc.)
-- indeed this could be thought of as an operational definition of interest: the amount of time given to something (attention is perhaps closer)

often, "the critical behavior is variable over a day or some longer time period. [...] behavior may shift as the hours or days of the week change." (136-7)
-- another fallow ground for a project to frustrate the expectations. self-aware installations that flower only when there is no movement?

"Both [random] time and locational sampling should be employed if possible, [...] population varies over time, and the content of their behavior similarly varies. If one can broaden the sampling base, he can expand the character of material available for study." (140-1)
-- powerfully integrates with the concept of artwork as individual subject of investigation: the 'behavior' of an artwork varies over time in its effects on its environment (people). The character of the material artwork grows in proportion to the attention it receives from society and the locale it affects.

"From symbols and shadows to the truth" - Cardinal Newman (187)