Density: How many per node?
Density summary table / dense / sparse /layered
Anchor density is basically the number of anchors on a node. The more anchors, the more choices are presented to a reader. This is not an either/or, but a scale--the question is how many anchors per node tips the scale over from sparse to dense, and which anchors count.
Anchor density vs. link density
Discussions about link density usually assume a one-to-one correspondence between anchor and link--that each anchor will lead to only one destination. Therefore, when analysts use this assumption to examine link density, they are really counting anchors and determining density based on the amount of visible anchors.
We hold, however, that a single anchor can connect to multiple links (e.g. Samplers ). Reagan Library  and What We Will both use a central anchor that users can spin around to access many destinations. Him  and War Games--Catch The LandMine!!  use the same 5 anchors and 1 anchor respectively to trigger randomly different content. Thus, a node with only one anchor can still be quite dense in terms of the number of links while remaining sparse in anchor density.
What are we counting?
There are several strategies to count anchors:
Overall node to anchor density
Even though Wyoming and Washington D.C.
have about the same number of inhabitants, the population density is quite
different. In the same manner, density must also be considered by ratio
of anchors per node in the work. While Sand
Loves  has only two links per node, the anchor ratio to node is
high, as there are only eight nodes. Conversely, Earthtrends
 has over 40 anchors in most secondary nodes, yet the anchor to
node ratio is low as the site offers material from a database with over
500 variables that provides information from over 200 countries.
Spatial density and layering
Where are we counting?
While all anchor properties are intertwingled, discussions of density depend on location (isolated, embedded anchors or anchor clusters in menus and maps). The numbers of anchors, and even the ratio of anchoral content to nonanchoral content is meaningless to defining a reading experience without considering the overall context of where those anchors are. For example, if we use the extrapolated Nielsen definition in determining anchor density, then a site that places anchors in anchor clusters and avoids embedded links (e.g. Nevada Division of Environmental Protection ), will always be seen as a sparsely anchored site. If we consider anchor density only in terms of the anchor's relation to the text, this may be quite correct. If we consider anchor density in terms of reader choices on a node, this seems incorrect--as the menus provide many choices per node.
Readers presented with anchors choose whether or not to follow the anchor. The function of anchors congregated in a menu or map seems to be fundamentally different from the function of embedded or content anchors. These anchors show the relationship of the content to the entire site or work, usually with hierarchical substructures. Expecting readers to trigger all of these anchors would be as absurd as expecting restaurant goers to order everything on the menu. So Khan and Locatis' assumptions of a connection between anchor density and confusion may not hold in densely anchored menus or maps as it does in sites with many anchors embedded in the content.
So what definition should we use?
As we only found a few sites that would truly qualify as sparse under even a liberal reading of Khan and Locatis or Nielsen (10 percent or less of the node's elements are anchoral), dividing sites into merely sparse and dense does not mean a great deal.
Efferent sites that had higher anchor densities tended to use menus rather than embedded anchors. If anchor density is counted merely as the ratio of anchors to text, then sites with menus and maps are dense sites. However, if anchor density is counted only in embedded content, then these sites are sparse, as they rarely had embedded anchors. Anchors embedded in the content involve more connective tissue and connotative relationships. Readers must stop their content reading to ponder the importance of the anchor and its relationship to the content.
Thus, density must take anchor clustering (in maps or menus) and anchor isolation (embedded anchors) into account. We would thus break density definitions down further into:
With this division, we can see that most of the efferent sites in our survey have a menu-driven density. This reliance may be because efferent sites are serving information that can readily fit into a hierarchical menu system, and thus can offer readers the particular information they are seeking. Aesthetic sites, on the other hand are more evenly divided between menu, content, and sparse strategies.
|Density summary table|