1. What is the difference between selection by attributes and selection by location? 

 Selection by attributes finds the commonalities among a group of objects by a particular attribute in a table.  Selection by location finds a particular feature in its relation to another specified spatial feature.

2. What is the difference between an attribute query and a definition query? 

 The definition query differs from the attribute query in that features satisfying an attribute query are selected, while features satisfying a definition query are displayed and the rest are hidden.

3. What steps would you use to begin a spatial join (as opposed to a join based on attributes)? 

 Right click the target layer, point to "joins and relates," click join.  In the Join Data dialog, choose "join data from another layer based on spatial location," then select the join layer.

4. If you want to select part of an existing layer (or shapefile or geodatabase) and create a new shapefile or geodatabase out of it that actually exists as a separate data file that you could put into another map document file, what two functions do you have to choose from? 

 clipping and exporting selected data

5. If you just want to take selected features from an existing layer and display them as a separate layer within the current map document file without creating a new data set, what steps would you perform? 

 First select the feature you wish to examine as a separate layer (select it on the map with the select features tool).  Go to the relevant layer in the table of contents and right-click on it.  Point to "selection" on the menu, and click create layer from selected features.  This creates the new layer.

6. What is the difference between a union and an intersect operation done on two polygon layers? 

 A union combines two polygons on two separate layers, making three distinct polygons (two original plus the overlap) on a single layer.  An intersect makes a new layer, but only shows the intersection polygon of the two original.

7. Which operation, union or intersect, can be done with a line layer and a polygon layer? 

 Union.  An intersection wouldn't make sense since only a line would appear.

8. What is the difference between a geographic coordinate system (GCS) and a projected coordinate system (PCS)? 

 A GCS is a graticule based coordinate system that can be measured in degrees.  The PCS is a system that defines location on a flat map based on (x,y) or (y,x) coordinates.

9. Let’s say you obtain a spatial dataset off the web and add it to an ArcMap file you are working on, but in the process you get the error message shown on p. 348 stating “One or more layers is missing spatial reference information.  Data from those layers cannot be projected.”  What application or program do you use to tell ArcGIS what projection the data is in? 

 Go to ArcToolbox and select "Data Management Tools."  Then select "Projections and Transformations."  Select "Define Projection Tool."  Select the layer you wish synchronize, then select the correct coordinate system on the menu provided.

10. Where do you find out what projection the data is in?  (Hint: This is “data about data.”) 

 Follow the directions in the previous answer and define projection box will tell you, or more simply, go to the layer in the table of contents of ArcCatalog, click the metadata tab and it will display the projection information.

11. For practice with this, go to the National Atlas Map Layers Warehouse (http://www.nationalatlas.gov/atlasftp.html).  What map projection is used for the “Land Cover Characteristics” GeoTIFF file? 

Lambert Azimuthal Equal Area.