Place-name choropleths: Difference between revisions

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{{#vardefine:vers|v<xmldoc path="bot/includes/kml" file="counties.xml" stylesheet="version.xsl"></xmldoc>}}
{{PlaceNamesChoropleths}}<div class="no-img">
{{#display_map:|centre=53.06473844328687,-1.5260696411132812|type=terrain|types=roadmap,satellite,hybrid,terrain|controls=pan,zoom,type,scale,streetview|width=34%|height=550|gkml=https://www.irhb.org/wiki/kml/england/country/dynamic/place-names/choropleth-count/england-no-styles.kmz?t=7|enablefullscreen=yes|copycoords=yes|kmlrezoom=yes}}<div class="pnMapLegend">Count of place-names per county. The darker green, the more the count for a given county exceeds the average for the 39 historic counties. The darker red, the further below average is the count. White represents values close to the mean.</div>
<p id="byline">By Henrik Thiil Nielsen, 2017-11-06. Revised by {{#realname:{{REVISIONUSER}}}}, {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}}.</p>This page includes a choropleth map of the English counties, detailing the geographical distribution of Robin Hood-related place-names and localities from three different perspectives. The choropleth can also be selected via a button below the map found in the top right corner of all those landing pages in IRHB's place-names section that deal with English place-names. From links in the text below the choropleth it is possible to switch between three modes: Count, Area, and Area/Population. Below is found discussion of these choropleth views, a list of colour codes and a table containing the dataset on which the views are based.
{{#display_map:|centre=53.06473844328687,-1.5260696411132812|type=terrain|types=roadmap,satellite,hybrid,terrain|controls=pan,zoom,type,scale,streetview|width=34%|height=550|gkml=https://www.irhb.org/wiki/kml/england/country/dynamic/place-names/choropleth-area/england-no-styles.kmz?t=7|enablefullscreen=yes|copycoords=yes|kmlrezoom=yes}}<div class="pnMapLegend">This map represents the same data as that above but takes the widely differing areas of counties into account.</div>{{#display_map:|centre=53.06473844328687,-1.5260696411132812|type=terrain|types=roadmap,satellite,hybrid,terrain|controls=pan,zoom,type,scale,streetview|width=34%|height=550|gkml=https://www.irhb.org/wiki/kml/england/country/dynamic/place-names/choropleth-area-pop/england-no-styles.kmz?t=7|enablefullscreen=yes|copycoords=yes|kmlrezoom=yes}}<div class="pnMapLegend">This map represents the same data as those above but attempts to take both areas and population densities of counties into account.</div>{{PnNavMapEnglishPlaceNames}}<div class="no-img"><p id="byline">By Henrik Thiil Nielsen, 2017-11-06. Revised by {{#realname:{{REVISIONUSER}}}}, {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}}.</p>This page includes choropleth maps of the English counties, detailing the geographical distribution of Robin Hood-related place-names and localities from three different perspectives. The dataset on which they are based is set out in a table below.  
 


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=== The choropleth maps ===
== The choropleth ==
A choropleth is something much more widely known than its name: a "thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map".<ref>[https://en.wikipedia.org/wiki/Choropleth_map Wikipedia: Choropleth map.]</ref> It thus resembles a heat map, but unlike a heat map in which variation is in principle continuous, it displays data averaged over discrete geographical regions, in this case the English historic counties. On all three maps, a bi-polar colour progression is used, counties with values above the mean &ndash; set to index 100 &ndash; being coloured a progressively darker green, while those below are coloured a progressively darker red. Areas with values close to the mean are white or nearly so. Ideally colour gradation should be linear, but since there are a few important outliers in the data, this could only be achieved with colour steps so small that they become difficult to discern or, on the other hand, such large intervals of values grouped together that resolution for values closer to the mean would be insufficient. Intervals are therefore larger for areas well above the mean.  I give a brief description of each map below. Population and area data for England and the historic counties are taken from the 1891 census.<ref>[http://www.histpop.org/ohpr/servlet/PageBrowser?path=Browse/Census%20(by%20date)/1891&active=yes&mno=64&tocstate=expandnew&tocseq=500&display=sections&display=tables&display=pagetitles&pageseq=first-nonblank Histpop - The Online Historical Population Reports Website: Population. Administrative counties, England and Wales. Vol. I, 1891 &ndash; Page vi] (University of Essex).</ref> Many place-names first figure in mid-19th century MS tithe awards or printed O.S. maps, so it would be natural to pick an earlier census as data source, but that of 1891 is the first one that provides a complete (surviving) dataset.  
A choropleth is something much more widely known than its name: a "thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map".<ref>[https://en.wikipedia.org/wiki/Choropleth_map Wikipedia: Choropleth map.]</ref> It thus resembles a heat map, but unlike a heat map in which variation is in principle continuous, it displays data averaged over discrete geographical regions, in this case the English historic counties.  
 
While Robin Hood-related localities in Greater London can be found on the [[London place-names]] page, for the choropleths they are assigend to the historical counties under which they belong, i.e. Essex, Kent, Middlesex or Surrey. Similarly, localities listed under the three historical ridings of Yorkshire are all assigend to Yorkshire here.
 
=== Simple county count ===
In Count view, the count of English place-names and localities currently covered on IRHB is divided by the number of historic counties. This figure is set to index 100 and used as the base for calculating the indexes for individual counties. Counties with an index value between 100 and 109 (both inclusive) are shown in white, those with higher values in progressively darker shades of green, those below 100 in increasingly dark shades of red. Since the counties vary so widely in size, we are here, as it were, comparing gooseberries to water melons and fruits of all sorts of intermediate sizes. Yet the main tendencies recur on the two following, more meaningful representations of the data.


==== Simple county count ====
=== Taking area into account ===
For the first map, the count of English place-names and localities currently covered on IRHB is set to index 100 and used as the base for calculating the indexes for individual counties. Counties with an index value between 100 and 109 (both inclusive) are shown in white, those with higher values in progressively darker shades of green, those below 100 in increasingly dark shades of red, Since the counties vary so widely in size, we are here, as it were, comparing gooseberries to water melons as well as fruits of all sorts of intermediate sizes. Yet the main tendencies recur on the next two, more meaningful representations of the data.
In the Area view, the density of Robin Hood-related place-names and localities in England &ndash; expressible as area in km<sup>2</sup> per place-name or vice versa &ndash; is taken as index 100 and indexes are calculated for individual counties based on their areas and counts of relevant localities/place-names. Colour gradation as on the first map.


==== Taking area into account ====
=== Taking area and population into account ===
For the second map, the density of Robin Hood-related place-names and localities in England &ndash; expressible as area in km<sup>2</sup> per place-name or vice versa &ndash; is taken as index 100 and indexes calculated for individual counties based on their land areas and counts of relevant localities/place-names. Colour gradation as on the first map.
The Area/Population view attempts to take area as well as population density into account. Here an expected place-name count is first calculated for each county based on its area and the average count per km<sup>2</sup> for England. On the basis of the population densities of England and the county in question we then adjust the expected figure upwards or downwards to reflect the population density of the county. This is done in linear fashion. The result is used as index 100 for the county, whose index value is then calculated on the basis of the actual count of place-names/localities. The colouring thus reflects the extent to which expectation is exceeded (or the opposite). It is an open question whether a statistician would find this procedure reasonable, but it obviously takes people to give places names, and it seems a reasonable assumption that population density has at least some influence on the density of named localities in a given area. It seems doubtful if this effect is linear, but without any relevant empirical knowledge, any adjustment that could be made to the way in which it is factored in would be arbitrary. Colour gradation as on preceding maps.


==== Taking area and population into account ====
=== A caveat ===
The third choropleth attempts to take area as well as population density into account. Here we first calculate an expected place-name count for each county based on its area and the average count per km<sup>2</sup> for England. On the basis of the population densities of England and the county in question we then adjust the expected figure upwards or downwards to reflect the population density of the county. This is done in linear fashion. The result is used as index 100 for the county, whose index value is then calculated on the basis of the actual count of place-names/localities. The colouring thus reflects the extent to which expectation is exceeded (or the opposite). I do not know whether a statistician would find this procedure reasonable, but it obviously takes people to give places names, and it seems a reasonable assumption that population density has at least some influence on the density of named localities in a given area. I doubt if this effect is linear, but as I have no relevant empirical knowledge, any adjustment I could make to the way in which it is factored in would be arbitrary. Colour gradation as on the preceding maps.
Keep in mind that the choropleths reflect the current state of affairs at IRHB. An estimated 200 place-names are still to be entered. Many of these, mostly of fairly recent origin, belong in the counties that are currently red on the maps.


==== Notes and qualifications ====
== Colour codes ==
While figures in the dataset table are updated once a day, it may take two or three days before the choropleths are updated. So when new material has just been added to the place-names section of IRHB and this ought to cause changes to the choropleths, you may find the table and maps slightly out of sync for a day or so. Keep in mind that the choropleths reflect the current state of my worky. An estimated 75 to 150 place-names are still to be entered, many of these, mostly of fairly recent origin, belong in the counties that are currently dark red on the maps.
In all three views, a tri-polar colour progression is used, counties with values above the mean &ndash; set to index 100 &ndash; being coloured a progressively darker green, while those below are coloured a progressively darker red. Areas with values close to the mean are white or nearly so. Ideally colour gradation should be linear, but since there are a few important outliers in the data, this could only be achieved with colour steps so small that they become difficult to discern or, on the other hand, such large intervals of values grouped together that resolution for values closer to the mean would be insufficient. Intervals are therefore larger for areas well above the mean. A brief description of each view is given below. Population and area data for England and its 39 historical counties are taken from the first (1801) census.<ref>[http://www.histpop.org/ohpr/servlet/PageBrowser?path=Browse/Census%20(by%20date)/1851&active=yes&mno=27&tocstate=expandnew&tocseq=13700&display=sections&display=tables&display=pagetitles&pageseq=first-nonblank Histpop &ndash; The Online Historical Population Reports Website: Population tables I, Vol. I. England and Wales. Divisions I-VII, 1851 &ndash; Page clxviii] (University of Essex). [https://www.google.com/search?q=acres+to+km2 Google: Acres to km2.]</ref>
<div class="expando-container" style="padding-top:2em;"><table class="bordertable" id="colors1"><tr class="header"><th>Limit (index)</th><th>Colour</th></tr><tr><td>Less than 10</td><td style="background-color:#a30000; width:1.5em;"></td></tr><tr><td>Less than 20</td><td style="background-color:#b70000; width:1.5em;"></td></tr><tr><td>Less than 30</td><td style="background-color:#d11919; width:1.5em;"></td></tr><tr><td>Less than 40</td><td style="background-color:#db4c4c; width:1.5em;"></td></tr><tr><td>Less than 50</td><td style="background-color:#e06666; width:1.5em;"></td></tr><tr><td>Less than 60</td><td style="background-color:#e57f7f; width:1.5em;"></td></tr><tr><td>Less than 70</td><td style="background-color:#ea9999; width:1.5em;"></td></tr><tr><td>Less than 80</td><td style="background-color:#efb2b2; width:1.5em;"></td></tr><tr><td>Less than 90</td><td style="background-color:#f4cccc; width:1.5em;"></td></tr><tr><td>Less than 100</td><td style="background-color:#f9e5e5; width:1.5em;"></td></tr><tr><td>Less than 110</td><td style="background-color:#ffffff; width:1.5em;"></td></tr><tr><td>Less than 120</td><td style="background-color:#f9faf9; width:1.5em;"></td></tr><tr><td>Less than 130</td><td style="background-color:#f3f5f3; width:1.5em;"></td></tr><tr><td>Less than 140</td><td style="background-color:#ecefec; width:1.5em;"></td></tr><tr><td>Less than 150</td><td style="background-color:#d9e0da; width:1.5em;"></td></tr></table><table class="bordertable" id="colors2"><tr><td>Less than 160</td><td style="background-color:#c7d0c7; width:1.5em;"></td></tr><tr><td>Less than 170</td><td style="background-color:#b4c1b5; width:1.5em;"></td></tr><tr><td>Less than 180</td><td style="background-color:#a2b1a3; width:1.5em;"></td></tr><tr><td>Less than 190</td><td style="background-color:#8fa290; width:1.5em;"></td></tr><tr><td>Less than 200</td><td style="background-color:#7c927e; width:1.5em;"></td></tr><tr><td>Less than 300</td><td style="background-color:#6a836b; width:1.5em;"></td></tr><tr><td>Less than 400</td><td style="background-color:#577359; width:1.5em;"></td></tr><tr><td>Less than 500</td><td style="background-color:#456447; width:1.5em;"></td></tr><tr><td>Less than 600</td><td style="background-color:#3e5a3f; width:1.5em;"></td></tr><tr><td>Less than 700</td><td style="background-color:#375038; width:1.5em;"></td></tr><tr><td>Less than 800</td><td style="background-color:#304631; width:1.5em;"></td></tr><tr><td>Less than 900</td><td style="background-color:#293c2a; width:1.5em;"></td></tr><tr><td>Less than 1000</td><td style="background-color:#223223; width:1.5em;"></td></tr><tr><td>Less than 1500</td><td style="background-color:#1b281c; width:1.5em;"></td></tr><tr><td>Less than 2000</td><td style="background-color:#141e15; width:1.5em;"></td></tr><tr><td>Otherwise</td><td style="background-color:#000000; width:1.5em;"></td></tr></table></div>


=== Dataset and colour codes ===
== Dataset ==
Click header to expand dataset.
Click header to expand dataset for England or each county/shire.
<div class="expando-container">
<div class="expando-container" id="dSet"></div>
<xmldoc path="bot/includes/kml" file="counties.xml" stylesheet="table.xsl"></xmldoc>
<xmldoc path="bot/includes/kml" file="counties.xml" stylesheet="colors.xsl"></xmldoc>
</div>


=== Background ===
== Background ==
* [http://www.histpop.org/ohpr/servlet/PageBrowser?path=Browse/Census%20(by%20date)/1891&active=yes&mno=64&tocstate=expandnew&tocseq=500&display=sections&display=tables&display=pagetitles&pageseq=first-nonblank Histpop - The Online Historical Population Reports Website: Population. Administrative counties, England and Wales. Vol. I, 1891 &ndash; Page vi] (University of Essex).
* [http://www.histpop.org/ohpr/servlet/PageBrowser?path=Browse/Census%20(by%20date)/1851&active=yes&mno=27&tocstate=expandnew&tocseq=13700&display=sections&display=tables&display=pagetitles&pageseq=first-nonblank Histpop &ndash; The Online Historical Population Reports Website: Population tables I, Vol. I. England and Wales. Divisions I-VII, 1851 &ndash; Page clxviii] (University of Essex)
* [https://en.wikipedia.org/wiki/Choropleth_map Wikipedia: Choropleth map.]
* [https://en.wikipedia.org/wiki/Choropleth_map Wikipedia: Choropleth map]
* [https://en.wikipedia.org/wiki/Heat_map Wikipedia: Heat map.]
* [https://en.wikipedia.org/wiki/Heat_map Wikipedia: Heat map.]


=== Notes ===
== Notes ==
<references/>
<references/>



Revision as of 22:46, 5 January 2021

Viewing choropleth • View choropleth • View choropleth • About the choropleths. County boundary data provided by the Historic Counties Trust.

By Henrik Thiil Nielsen, 2017-11-06. Revised by Henrik Thiil Nielsen, 2021-01-05.

This page includes a choropleth map of the English counties, detailing the geographical distribution of Robin Hood-related place-names and localities from three different perspectives. The choropleth can also be selected via a button below the map found in the top right corner of all those landing pages in IRHB's place-names section that deal with English place-names. From links in the text below the choropleth it is possible to switch between three modes: Count, Area, and Area/Population. Below is found discussion of these choropleth views, a list of colour codes and a table containing the dataset on which the views are based.


The choropleth

A choropleth is something much more widely known than its name: a "thematic map in which areas are shaded or patterned in proportion to the measurement of the statistical variable being displayed on the map".[1] It thus resembles a heat map, but unlike a heat map in which variation is in principle continuous, it displays data averaged over discrete geographical regions, in this case the English historic counties.

While Robin Hood-related localities in Greater London can be found on the London place-names page, for the choropleths they are assigend to the historical counties under which they belong, i.e. Essex, Kent, Middlesex or Surrey. Similarly, localities listed under the three historical ridings of Yorkshire are all assigend to Yorkshire here.

Simple county count

In Count view, the count of English place-names and localities currently covered on IRHB is divided by the number of historic counties. This figure is set to index 100 and used as the base for calculating the indexes for individual counties. Counties with an index value between 100 and 109 (both inclusive) are shown in white, those with higher values in progressively darker shades of green, those below 100 in increasingly dark shades of red. Since the counties vary so widely in size, we are here, as it were, comparing gooseberries to water melons and fruits of all sorts of intermediate sizes. Yet the main tendencies recur on the two following, more meaningful representations of the data.

Taking area into account

In the Area view, the density of Robin Hood-related place-names and localities in England – expressible as area in km2 per place-name or vice versa – is taken as index 100 and indexes are calculated for individual counties based on their areas and counts of relevant localities/place-names. Colour gradation as on the first map.

Taking area and population into account

The Area/Population view attempts to take area as well as population density into account. Here an expected place-name count is first calculated for each county based on its area and the average count per km2 for England. On the basis of the population densities of England and the county in question we then adjust the expected figure upwards or downwards to reflect the population density of the county. This is done in linear fashion. The result is used as index 100 for the county, whose index value is then calculated on the basis of the actual count of place-names/localities. The colouring thus reflects the extent to which expectation is exceeded (or the opposite). It is an open question whether a statistician would find this procedure reasonable, but it obviously takes people to give places names, and it seems a reasonable assumption that population density has at least some influence on the density of named localities in a given area. It seems doubtful if this effect is linear, but without any relevant empirical knowledge, any adjustment that could be made to the way in which it is factored in would be arbitrary. Colour gradation as on preceding maps.

A caveat

Keep in mind that the choropleths reflect the current state of affairs at IRHB. An estimated 200 place-names are still to be entered. Many of these, mostly of fairly recent origin, belong in the counties that are currently red on the maps.

Colour codes

In all three views, a tri-polar colour progression is used, counties with values above the mean – set to index 100 – being coloured a progressively darker green, while those below are coloured a progressively darker red. Areas with values close to the mean are white or nearly so. Ideally colour gradation should be linear, but since there are a few important outliers in the data, this could only be achieved with colour steps so small that they become difficult to discern or, on the other hand, such large intervals of values grouped together that resolution for values closer to the mean would be insufficient. Intervals are therefore larger for areas well above the mean. A brief description of each view is given below. Population and area data for England and its 39 historical counties are taken from the first (1801) census.[2]

Limit (index)Colour
Less than 10
Less than 20
Less than 30
Less than 40
Less than 50
Less than 60
Less than 70
Less than 80
Less than 90
Less than 100
Less than 110
Less than 120
Less than 130
Less than 140
Less than 150
Less than 160
Less than 170
Less than 180
Less than 190
Less than 200
Less than 300
Less than 400
Less than 500
Less than 600
Less than 700
Less than 800
Less than 900
Less than 1000
Less than 1500
Less than 2000
Otherwise

Dataset

Click header to expand dataset for England or each county/shire.

Background

Notes