All Rated Libraries
Each circle in this chart represents one US public library. Move cursor over any circle to view that library's data. Click on Expenditure Category legend to highlight individual expenditure categories. categories. (Chart response may be slow. Click once then wait.) To remove category highlighting, click on blank white area to right of legend.
This chart depicts all libraries meeting the LJ Index rating criteria in November 2011. These ratings were based on 2009 public libraries data from IMLS. N=7,513 in the chart title indicates the number of circles on the graph, which corresponds with the total number of libraries rated.
The chart's horizontal axis (population) uses an uneven logarithmic scale. This helps the individual circles for smaller libraries to be more visible. The chart below shows the same data with regular axis scaling.
In the chart above note that with logarithmic scaling each axis tick-mark increases 10-fold compared to the prior mark. This allows circles to the left of the chart to be more spread out, while still allowing the largest libraries to fit on the chart. For this reason distances visible between symbols nearer the right end of the axis represent larger spans than the same distances at the left end.
This chart's vertical axis (LJ Index score) uses evenly-spaced scaling. The population axis starts at 1,000, the smallest population service area libraries must serve to qualify for an LJ Index rating.
Other charts in this series use logarithmic scaling for the vertical axis also. In these instances, distances between symbols toward the bottom of the vertical axis represent smaller values than the same distances higher up. See also the chart of Rated Libraries Serving Populations of 50,000 or Less, which uses an alternative approach to this spacing problem.
The next chart demonstrates the spacing problem discussed above.
This chart depicts the same data as in the first chart above, except without logarithmic axis scaling. Rather, it uses evenly-spaced scaling for both chart axes. Use of regular scaling like this obviously makes examining the distribution of smaller libraries difficult.
© Ray Lyons 2011. All rights reserved.