Sarah Pope's Map Catalog

Sunday, April 24, 2011

Stem and Leaf plot

A stem and leaf plot is a graphical way to display statistics and gives the reader a quick representation of the distribution, shape and density of the data. In statical terms, the mode and outliers are easily identified by just looking at the chart. Stem and leaf plots, like the one above, uses the first significant digit as the "stem", divided by a line, and the second significant digit as the "leaf." Each stem is only listen once, but a leaf digit could be repeated if a number is duplicated.

Box plot

A box plot graphs numerical data through 5-number summaries; the smallest observation, lower quartile (Q1), median (Q2), upper quartile (Q3), and largest observation. The three quartiles are marked with a box, and the smallest and largest observations and marked with the end points of the line. The spacings between each box can differ depending on the degree of dispersion and skewness of the data.

Histogram

Histograms are used to display the distribution of data and the probability of a continuous variable. They also predict the density of the data, with the total area always equaling 1. Consistent intervals are marked on both the x- and y- axis, which shows equal frequencies of observations. This example is showing the relative number of employees a business has and the salary that each employee (on average) makes. It predicts that those working in companies with 500+ people, are only making half the salary as those with 10 or fewer, or 88 and more employees.

Parallel Coordinate Graph

Parallel coordinate graphs are used analyze multivariate data and the geometry of multidimensional problems that are not satisfied by our 3D perceptions. It displays a group of lines containing a set of points separated by equally spaced vertical lines. This is an example from Alfred Inselberg, who invited the parallel coordinate who says this coordinate system can be applied to air traffic control, visual data mining, and interactive models of other complex systems.

Triangular Plot

Triangular plot, also known as a ternary plot, depicts the ratios of 3 variables which sums to a constant (1.0) that is positioned in an equilateral triangle. A lot of times it is used in physical sciences to show the relations between species and substances. The example above shows the data plotted in 3 bivariate cross-plots (AB, BC, AC) which translates onto the triangular diagram, where means and standard deviations are calculated.

Windrose

The windrose is used by meteorologist when graphing weather conditions and the wind speed and direction at a specific location. The different colored bands represent the wind ranges. The direction of the winds with the longest band shows the wind direction with the greatest frequency. Typically windroses will use 16 bands, each representing a different cardinal directions- but can be subdivided into as many as 32 directions. A practical application is the importance of a windrose when construction an airport runway, as wind speed and direction effects airplanes take-offs and landings.

Climograph

Climographs are used to show climatic temperatures and precipitation of a certain area. This example of a climograph show the precipitation and temperature levels in Guam, graphed by month from January to December. Although there was a lot of variation in the precipitation levels, the temperature stayed relatively stable.

Saturday, April 23, 2011

Population Profile

Population profile is a graph analyzing the extent to which a group of people exhibit a certain quality or characteristic. Both x- and y- axis are labeled with the analyzing factor range, and the graph consists of horizontal bars. This example looks at the amount of immigrants into the United States in 2004, separated by male and female and their ages. The graph analyzes the potential change in demographic transition; it shows that more than half of immigrants entering the country are 25-39 years of age.

Scatterplot

Scatterplots uses a coordinate plane to display two variable for a set of data. Marked as a collection of points, each point has a value of two variables- one from the x-axis and one from the y-axis. The collection of points are related to each other in what is known as the correlation- positive (rising), negative (falling) or uncorrelated (completely scattered). This example is for an experiment that is measuring a explanatory variable and a response variable, having a positive correlation.

Index Value Plot

Index Value

Index value plot does not show absolute values, but instead an index of measurements. This example is of the air quality index value for statistical areas, showing the overall quality of air concerning all available pollutant measurements.

Accumulative Line Graph or Lorenz Curve

Lorenz Curve

Accumulative line graph, or Lorenz curve, is a graph that shows the degree of inequality between two variables distributions. The slope can be measured which will determine the value of the difference between the two variables. Because the lorenz curve combines the values in each category, it is not comparing the two to each other but instead considers the whole graph and increasing or decreasing.

Bilateral Graph

A bilateral graph compares 2 or more variables side by side, relative to a bar graph. This example has a x-axis regarding the fiscal years and the y-axis is counting the number of people. The data in the graph is measuring the acceptance of trainees, dispatch of experts, and dispatch of JOCVs.

Nominal Area Choropleth Map

Nominal area Choropleth map

Nominal area choropleth maps are maps that represent nominal values, measured in amounts but not in an actual value. In order to show the information accurately, data is usually given in quantitative values. This is an example from the presidential election in 2008 and the predictions of the states being "blue" or "red." This specific map determined the democrats would win just based on the information in the media or other forums.

Unstandardized Choropleth Map

Unstandardized choropleth maps use data with raw sets of numbers. These raw numbers represent the total value and are not averaged together. This example is a representation of total fertility rates from 2000-2005 in the nation. The legend explains that the lighter shaded continents have lower fertility rates than the darker shaded continents.

Standardized Choropleth Map

Standardized choropleth maps are used to compare the distribution among an area, usually shaded to demote the difference and variance. In this example, the map of Canada is comparing the population percentage of 14 year olds and younger in 2006. The lighter the shading the lower the population, and the darker the shading the higher the percentage.

Univariate Choropleth Map

A univariate choropleth map only displays one set of variables or data. Again, different shades of colors are used to represent the difference between each category. This example represents the percentage of individuals living in poverty in 2000, classified by county.

Bivariate Choropleth Map

Bivariate choropleth map shows two separate variables and data sets regarding a certain issue. Usually, different colors are used to shade and decipher the difference in the variables. This example of a bivariate choropleth map shows Russia's population density in 2002 regarding percentage of population change from 1989-2002 and Russia's central federal district.

Unclassed Choropleth Map

Unclassed choropleth map is a unique technique in that it does not necessarily assign the data to any form of classification or grouping. Instead, continuous color schemes and shading are used to correlate the data to the values. This example shows this color scheme and the related values on the continuum.

Classed Choropleth Map

A classed choropleth map provides visualization of how a measurement varies across an area, or the level of variability across a region. Shading is used to show this proportion of statistical measurements. Having too many classes for a map can make it more difficult to read and the colors can distort the actual information; 4 or 5 classes is usually enough. This choropleth map shows the amount of spending by overseas residents in 2003.

Range Graded Proportional Circle Map

Range graded proportional circle map

A range graded proportional circle map uses circles to group the data into circles, keeping in mind their relative sizes that depicts the data being displayed. Circles are used because they are easy to scale and measured using the radius. This example shows the population of Europe by country, by using relatively different circle sizes in the map, you can easily distinguished the different populations.