update compare, map page descs for #2

src/overview.md

@@ -3,51 +3,54 @@
 This chapter provides an overview of the three main pages of the [Urban Analyst
 platform](https://urbananalyst.city):
 
-- [Map](https://urbananalyst.city/maps) showing interactive maps for each
-  city;
 - [Compare](https://urbananalyst.city/stats) comparing aggregate statistics for
   all cities; and
+- [Map](https://urbananalyst.city/maps) showing interactive maps for each
+  city;
 - [Transform](https://urbananalyst.city/transform) for transforming any chosen
   city to become more like other cities.
 
-## Map
+## Compare
 
-The [Maps page](https://urbananalyst.city/maps) is the first and main page of
-Urban Analyst. This page shows interactive maps for each city, with values for
-all UA variables displayed in small polygons. These polygons are defined by
-city-specific assessments of spatial disadvantage. Berlin, for example,
-regularly measures a compound index of social disadvantage aggregated into XX
-polygons. The map for Berlin uses these polygons provided by the city to
-aggregate all measured variables. The variables are described in a [subsequent
-chapter](./variables.md).
-
-As in all UA measurements, lower values of all variables are generally better
-than higher values. Colour scales on all maps thus generally display lower
-values in brighter, yellow colours, while higher values are displayed in
-darker, blue or violet colours. The control panel includes an "Explain Layer"
-button which opens a text panel explaining details of the chosen variable.
+The [Compare page](https://urbananalyst.city/compare) is the first and main
+page of Urban Analyst, enabling the properties of all UA cities to be compared.
+A pull-down panel enables each variable or "layer" to be selected. The page
+then displays a graphical representation of values of the chosen layer for all
+cities. As in all UA pages, lower values are generally better than higher
+values. The control panel includes an "Explain Layer" button which opens a text
+panel explaining details of the chosen variable.
 
 ### Single and Paired Variables
 
-The control panel of the [maps page](https://urbananalyst.city/maps) enables
-each variable to be selected, with the map being updated on each selection to
-display the spatial distribution of the chosen variable. The control panel also
-includes an option to select "paired" variables. The resultant maps then
+The control panel of the [compare page](https://urbananalyst.city/compare)
+includes an option to select "paired" variables. The resultant graphs then
 display the strength of relationship between any chosen *pair* of variables.
-
-For example, choosing social index and the nature index will
-display the strength of relationship between access to natural spaces and
-social disadvantage. Both of these variables are measured such that low values
-are better than high values. A positive relationship between the two would then
-mean that lower social disadantage is coupled with better access to natural
+For example, choosing social index and the nature index will display the
+strength of relationship between access to natural spaces and social
+disadvantage. Both of these variables are measured such that low values are
+better than high values. A positive relationship between the two would then
+mean that lower social disadvantage is coupled with better access to natural
 spaces, while high social disadvantage is coupled with worse access to natural
 spaces. Conversely, a negative relationship would indicate that higher social
-disadantage was coupled with better access to natural resources. Or, in the
+disadvantage was coupled with better access to natural resources. Or, in the
 words brought up by clicking the "Explain Layer" button, "Low values indicate
 that good access to natural spaces is coupled with disadvantageous social
 conditions."
 
-## Compare
+## Map
+
+The [Map page](https://urbananalyst.city/map) shows interactive maps for each
+city, with values for all UA variables displayed in small polygons. These
+polygons are defined by city-specific assessments of spatial disadvantage.
+Berlin, for example, regularly measures a compound index of social disadvantage
+aggregated into XX polygons. The map for Berlin uses these polygons provided by
+the city to aggregate all measured variables. The variables are described in a
+[subsequent chapter](./variables.md).
 
+As in all UA measurements, lower values of all variables are generally better
+than higher values. Colour scales on all maps thus generally display lower
+values in brighter, yellow colours, while higher values are displayed in
+darker, blue or violet colours. The control panel includes an "Explain Layer"
+button which opens a text panel explaining details of the chosen variable.
 
 ## Transform