Modelbuilder question from student

Discussion created by courtneywchandler1 on May 6, 2014
Hi, I am working on a challenge in the Getting to Know ArcGIS Modelbuilder book and having issues with Challenge 1 (located in Appendix A, page 294 for those who may have the book handy). Here is the description of the challenge:

The economic development director for Oleander, Ms. Houston, has a project that deals with the tax revenues from single-family housing. She would like to be able to enter a tax rate, and then apply it to the current land values and see what the total tax revenues would be.

The tax values in the Property Data feature dataset, which is in the CityofOleander geodatabase within the Data folder. In the exercise, the most current data hasn't come out yet from the tax office, but you can build and test the model using the field TaxVal06. The tax rate for Oleander is 49 cents per $100 of valuation. The calculation then is (TaxVal06 x .0049). Ms. Houston will want to enter different tax rates and see the corresponding change in revenues. For this exercise, build in some error checking to make sure the rate entered is between 25 cents and 75 cents. If the number entered is out of this range-- for instance, 0.25 instead of 25-- correct the value and continue with the calculation. You can isolate the single-family properties by finding all the features where the field DU (dwelling units) = 1.

Before you take on the challenge, examine all the steps needed to complete the task:

-Prompt the user to enter a tax rate
-Perform error checking to make sure that an appropriate value was entered.
-Select all the single-family property (DU=1)
-Perform the calculation and display results.

So, my questions are do I begin with adding the Calculate Value tool to my model window? If so, how do I set up the expression TaxVal06 x .0049?

Next, the error checking, would that be an if-elif-else statement? If so, how would I set that up for a range (25-75)?

Any other hints/tips would be greatly appreciated!