Are We Heading Towards Another Housing Bubble? NO

DLG

http://limnology.wisc.edu/lake_information/mendota/mendota.html
A DLG (digital line graph) in the form of a hydrographic map. DLG is digital vector data. Data about map features are stored as lines (arcs), points, and areas (polygons). The lines in this map representing depth in meters of Lake Mendota.

DRG Map

http://www.nettally.com/biernack/boggybay.htma
DRG (Digital Rastor Graphic) is a scanned and georectified USGS topoquad. This graphic makes it possible to find geographic coordinates for a particular location. This map shows a DRG of Bobby Bay, Florida and surrounding areas.

Correlation Matrix

http://www.idrc.ca/en/ev-114381-201-1-DO_TOPIC.html
Correlation matrices are often used in social research to show significance between variables. This correlation matrix is showing variables in the determination of a measure of digital poverty. Due to the fact that the same variables are across both axes, the boxes in the upper right portion are left blank because they only mirror the bottom half of the chart and the "1" in the boxes on the diagonal are so due to the variables being perfectly correlated to themselves.

Isopleths

http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/water_nitro/water_and_nitrogen_cycles.htm
Isopleth maps like this one showing the sensitivity to PH levels in acid rain show levels of equal distribution of a variable across an area. Isopleths generally connect geographical or meteorological phenomena but can be used for other phenomena as well.

Similarity Matrix

http://www.lonestarbands.com/bmi.asp
Here's a similarity matrix displaying height and weight and their correlation to what would be considered normal weight, overweight, and grades of obesity by use of Body Mass Index. We can see if we fall along a line of similarity with a current height and weight we fit into one of these categories.

Isopach

http://www.geology.ohio-state.edu/~vonfrese/gs100/lect35/index.html
This map shows the thickness of Cambrian rocks, mainly limestone and shale in North America using isopachs to display the levels of density. Isopachs connect points of equal thickness in different kinds of rock and sediment formations.