Notes on Importing and Analyzing
Spatial Data Using ArcGIS

The basic steps include

1. Start Excel and load the file(s) that will be used in the analyses
2. Identify appropriate columns that are to be used in the analysis
3. Develop and construct calculations that will be used to perform the time series analysis (e.g., subtract POP90 from POP99 to examine the change in population during this period)
4. Save the file in dBase format (*.dbf)

The basic steps include

1. Start ArcGIS
2. Loaf an existing ArcGIS Document (*.MXD) or click cancel.  The system will prompt you to add data.  If you know what you want, locate it and click the add button.  Otherwise, click cancel.
3. New map layers containing the map data (e.g., counties) can also be added by clicking on File --Add Data.  Sample data containing all of the US counties, as well as other features such as country and state boundaries, can usually be found in the C:\arcgis\arcexe81\Bin\TemplateData\USA directory. 
4. Use a query to select the subset of map data you need for your analysis.  Use Selection - Select by Attributes
5. In the Select by Attribute dialog box, select the state name column and enter a query to select the counties (you may need to expand the list of states available).
6. Save the selected counties to a separate map file.  Right click on the Layer in the contents window and select Data - Export Data.  Make sure that the Selected Features option is selected, give the file a name, and click OK to save the new map features.
7. When ArcGIS asks you if you want to add the features to the current map as a Layer, click "yes."
8. You can now close the original counties map and work from the IA counties layer.  You can repeat this for state data as well as other features of interest.

The basic steps include

1. Click the right mouse button on the theme
2. Select the Joins and Relates option
3. Select the option Join on the submenu
4. In the option, What do you want to join to this layer? Select Join attributes from a table
5. In option 1, select the name of the column in the map's table to use to link to an external table
6. In option 2, type or browse for the name of the file you will link to the map table.
7. In option 3, select the column from the imported table to use to join the tables 
8. Click OK to link the tables

1. In the map's window, double click on the layer in the contents windows (the left window)
2. In the Layers Property window select the tab for Symbology. 

1. The purpose of the Graduated Color option is to create a thematic map, a map which shows categories of data using varied colors or other symbology.
2. Click on the Quantities option (it is called quantities because it is designed to work with value or numeric data).
3. Select the option that you would like to use to display your theme; for example, graduated color.
4. The most important step is to select the field that you wish to use to create the graduated color theme.  Use the combo box to select the available fields from the list.
5. When you select a field, five categories of data will appear on the lower part of the window; if the categories are adequate, select Apply to have the theme appear on the map
6. Normalization allows you to select a field to use to normalize the data. 
7. If you want to change the values used to break the categories, change the numbers under the Value column
8. If you want to change the number of groups that will be displayed, select and change the classes option
9. Once completed, click the Apply button to change the map, close the Layers Properties by clicking on the OK button
10. To change an existing thematic map, double click on the theme in the table of context
11. A similar procedure is used for graduated symbols, dot density, and proportional symbols

1. The purpose of the Chart option is to create bar charts or pie charts that are overlaid on top of a map. This can be used to display information about multiple data fields simultaneously on the map
2. Click on the Charts option
3. A list of fields will show up under the Field Selection column
4. To add a field to the chart, click on the field in the Fields column and select the Right arrow button
5. To remove a field from the chart, click on the field in the right Field column and click on the Left arrow button
6. To change the color of a field in the chart, double-click on the color box for the field
7. To change the type of chart, click on the chart type in the left window
8. To change the properties of the chart (e.g., the size of the charts), click the Properties button
9. Once completed, click the Apply button to change the map and then close the dialog window
10. To change an existing chart on map, double click on the theme in the table of context
11. When using charts, you should be careful to think about what groupings of data are relevant and how they should be brought together.  For example, a pie chart is meant to show how much each component is as a relative percentage of the whole.  If your data do not represent such aggregated groupings, it makes no sense to use a pie chart. 

If you use Excel to preprocess data and encounter difficulties, the GIS Lab staff have suggested the following procedure to ensure that data are handled properly (in my experience, this procedure works every time):

In Excel, you need to specifically format the numbers to number and specify the number of decimal places since they are not the same for all 4 columns. The key is to set the database name definition that tells the .dbf the extent of the data once it gets converted. In Excel, go to Insert/Name/Define and in the box that pops up should be a Name called Database. If not, add one that is. The extent should include the first cell with data down to the last cell with data. Click "ok" and save to .dbf.  
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Questions about the GIS lab can be addressed to:

Robin McNeely, GIS Lab Manager
ISU GIS Facility
Rm 218, Durham, Iowa State University
Ames, IA 50011
515/294-2087
mobes@iastate.edu