Section Three: Creating Thematic Maps

Part Two: Creating Graphs

Creating graphs

MapInfo can also be used to create graphs of the variables in the tables. We will create a graph to show the number of people in each ethnic group in each ward of Bradford in 1991, as an example.
Hint

Data in tables which are not mappable may be used to create graphs.

Window > New Graph Window or choose the New Grapher button on the toolbar.
Creating a graph is done using a two stage wizard.

The Create Graph wizard may also be accessed by choosing the Create Graph option from stage 3, Analyse, of the Mapping Wizard Tool.

Step One: Choose the type of graph you require from the menu on the left. Choose an appropriate subtype from the preview window on the right. For our example, we will choose a column graph using the Clustered template. Click next.

Step Two: Choose the table in which the variable you wish to create a graph of is stored from the drop down menu at the top.
Select the field(s) from the table you wish to make a graph of. Click the Add>> button to add these fields to the graph. For this example, select all the fields except the total population.
If you wish to add variables from more than one table, choose the next table from the drop down menu at the top and add fields from it in the same way.
Choose the field with which you want to label the x-axis of your graph. Choose whether the series is in rows or columns. In our case, the series is in columns. Click OK.
The axis across the bottom of the graph is the x-axis, which is used to show the independent variable, i.e. the variable against which the dependent variable, which is on the y-axis (up the side of the graph) is measured. In our example the x-axis would show the ward, and the y-axis a count of people in each ethnic group.

Graphs often require a lot of modification. Graphs should have appropriate descriptive titles, and the axes should be appropriately labelled. The graph should be sized such that all the columns are clearly visible. This can be achieved using the options from the Graph menu, which appears when you create a new graph window. Make sure the graph you wish to modify is the active window, and choose from the appropriate options below. The most important thing about your graph is that it is clear.

Graph > Formatting... Allows you to change the colour scheme of your graph. It is advisable to make all other changes to your graph before changing the colour scheme, in order to ensure its clarity.
Graph > General Options This is an important menu item for improving the clarity of the graph. The General tab allows you to alter the distance between graph items, and their depth (if any). The tabs have preview windows so that you can see how your changes will affect the final graph. The Look tab allows you to change the position of labels in relation to other items. The Display Status tab allows you to hide the legend, but don't!
Graph > Series Options Select the series which you wish to modify by clicking on it before selecting this menu item. This item allows you to add data labels or trendlines. Data labels are only appropriate for graphs with few items, otherwise the graph becomes too cluttered, and trendlines are only appropriate for certain types of graph such as scattergraphs.
Graph > Grids and Scales Allows you to alter the gridlines that are visible and the positions of the axes in relation to the graph. The Category Axis is MapInfo's term for what is commonly known as the x-axis.
Graph > Titles Give your graph an appropriate title, such as "A stacked column graph to show the population of Bradford by ethnic group, at ward level, for the 1991 census." Make sure you label the y-axis. Make sure the boxes for items which you do not want to label are blank. Click Apply, then OK.
Do not forget to source your data. This may be a legal requirement, depending on where you got your data. If it is a legal requirement to inclide the data source, the source will say so explicitly, but it is good practice to include the data source anyway. You could use the footnote option from the Titles menu item for this.
Graph > 3D Viewing Angle If you have chosen a three dimensional type of graph, this option allows you to change the angle from which it is viewed.
Graph > Save As Template Allows you to save your graph setting as a template for future use.
The options from the graph menu are also available by right clicking on the appropriate graph.
The graph and legend may be resized and moved using the mouse. The legend may be formatted by selecting items within it, right clicking, and choosing formatting, for example, to change the colour of a series.

On to Section Three, Part Three: Creating Layouts

Section Three
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