China's 1990 Census: all the variables

(if you're still a bit shaky about how to do the various steps, keep a browser window open to the instructions from Tuesday's class, which are at miley.wlu.edu/gis/easia/av26sept.html, and refer to them as needed)

Open the Theme Table for that .shp file and check out what's included by scrolling across and looking at the column labels. What you have is more than 400 variables for the counties of your Province... more than you could ever want to know. Many of the columns are labeled with a number, but some of the most useful have had text substituted (Totalhouse, Totalpop, Totalmale and so on) to make them easier to find. There's a key to the census variable numbers available at miley.wlu.edu/gis/easia/1990census.html, also linked on the course home page as "1990 Census variables").

This dataset gives you LOTS of information about your Province, but needs to be used with some care. Any time you create a map and save it by capturing the image onto a web page you need to be sure to label it with the variable name(s) you used so you can interpret it later.

Try this out by double-clicking the raised label to open the Legend Editor, changing Legend Type to 'Graduated Color', choosing "Totalpop" as the Classification Field, then "Totalhouse" as the Normalize By. You're dividing the total population of each county by the number of households in that county. Would it make any sense to do it the other way around?

The result is a pattern, a distribution of Mean Household Size. What does it mean? What creates the variation you observe? We don't know ...or more exactly we don't have enough information to explain the observed distribution. It may turn out to be correlated with something else, or may be caused by something else...

But this time we won't use clunky old Word to display the result. We'll use a vastly more powerful and elegant tool: PhotoShop. Here are the steps:

1. From the Windows Start menu, select Programs, then Adobe, then PhotoShop5.5 and wait while it loads.
2. Once things have settled down and you see a grey screen, hit <Control><n> (a shortcut for "New") and you'll see a 'New' palette offering you an image size of 800 x 600 pixels.
3. Click 'OK' and hit <Control><v> to paste the Clipboard image into the space provided.

4. Now use PhotoShop's Rectangular Marquee Tool to define the area you want to save as an image. I suggest that you keep the map's Legend, showing the values of the colors.
5. Save the outlined area to the Clipboard with <Control><c> ('Copy'), do <Control><n> to get a New window again (and notice that its size is NOT 800x600 pixels), click 'OK', and then do <Control><v> to paste the Clipboard's contents into that new window.

   So far so good.

6. The next thing you'll do is SAVE this image to your /anth/ folder, but first you'll need to FLATTEN it.
7. From PhotoShop's Layer menu, choose 'Flatten Image'.
8. THEN you can go to PhotoShop's File menu, choose 'Save As...', navigate to your /anth/ folder, and save the image as a .jpg or .gif, naming it so you can find it again (like 'xhhold.jpg' for "mean household size"). Accept what PhotoShop gives you for Image Options.

9. This puts the saved image where you can include it on a web page, using the Image button in Netscape composer. You'll need to specify the image's whole URL, like http://home.wlu.edu/~yourusername/anth/xhhold.jpg), but the result should be MUCH better than what pasting the clipboard into a Word document can do. Try this on a new page (using Netscape Composer) and save the page as pshop1.html in your /anth/ folder.

You'll need to do this a few times to build confidence, but it will make your maps much more eloquent. When you're through trying it all out, close PhotoShop and say NO to saving the image --it's your original screen capture and isn't useful for anything.