Urban Libraries Council Member Libraries 2008 IMLS Statistics

Introduction

This series of charts presents statistical data for 118 libraries that are members of the Urban Libraries Council (ULC) as of 2010. The charts are presented as an exploration in the use of data visualization tools to present smaller sets of library data, as opposed to large, nationally aggregated datasets.  This study is solely the work of this author and has no official connection with the Urban Libraries Council.

The statistics are from the public library data issued by the Institute for Museum and Library Services in May 2010.  These data were reported to IMLS by over 9000 U.S public libraries to document the libraries' operations in 2008.  The designation as ULC member comes from the ULC membership roster.

 

Instructions

Navigating the Charts

Two types of charts appear in this series—bar charts and two-dimensional charts known as a "scatter plots." The series presents data describing ULC libraries in both of these formats for the items listed below. The items in the list are also links that can be used to access each measure type directly:

Each page in this series contains one or more charts. The names of charts appear at the top of each page in list format, followed by the first chart for that page. A horizontal menu at the top of each page contains these links:

Bar Charts

Here's an example of the bar chart format used in this series:

 

Bar Chart Example

 

The bar charts are formatted like a list, displaying each library's name in a row along with a horizontal bar depicting the statistical measure. A vertical dotted line extends the height of each chart indicating the median value for the measure.

The bar charts are accessible using the VIEW CHARTS menu item above. The charts are interactive (although the example above is not). When viewing the charts, move the cursor over any bar to see the measure's value for that specific library. Since the charts are in landscape orientation, not all 118 ULC libraries can be viewed at once. Use the chart's vertical scrollbar to view libraries not visible. If the chart displays a horizontal scrollbar, click on that scrollbar to see any information that may be out of view horizontally. Using the 'Export' icon at the bottom center of any chart, the unabridged chart can be saved as an image or in a PDF. In this format the chart is full-length with all libraries visible.

For each generic statistical measure in this series, two bar charts present data for ULC member libraries. One chart lists the libraries according to the magnitude of the data from low to high. e second bar chart lists the same data in alphabetical order by library name. A third chart follows these two presenting the same measure as a per capita rate (or sometimes a rate per 25,000 population) with libraries sorted by rate, low to high.

 

Two-Dimensional Scatterplots

A scatterplot is a graph that simultaneously represents two characteristics of single entities (individual ULC libraries in this case) by the location of symbols in a two-dimensional area.  In the example chart below the two characteristics are circulation per capita (vertical axis) and community population size (horizontal axis).  In the chart each library is represented by a circle whose location depicts two measures:  The circle's  height indicates the library's circulation per capita while its horizontal location indicates the size of the population served.  As examples, two circles in the chart are annotated with the library names and their respective values, circulation per capita and population. 

The scatterplots in this series permit the user to display these values interactively for any individual library.  Further information about this appears at the top of each page of charts. Some scatterplots use "logarithmic" axis scaling to improve the viewability of the data. This use is explained further in the section, An Explanation of Logarithmic Axis Scaling.

 

Scatter Plot Example

 

© Ray Lyons 2010. All rights reserved.