Quantitative Reasoning and the Environment          return to enviromath home page
Applet Information
      

Overview
Integrating the Applets with Quantitative Reasoning and the Environment
Help for FunctionLab and DifferenceEqLab
Help for StatCrunch

Overview                             top

Java applets are small programs (applications) that can be run directly on an internet browser, such as Internet Explorer, Firefox, or Mozilla. Make sure that you have Java enabled in your browser. For Internet Explorer on Windows go to "Internet Options," click the Security Tab, and make sure that "Java permissions" are enabled. You also should enable "scripting of Java applets." PC computer users running Windows may need to install Java. To get Java for Windows, click here. Modern Mac computers running the latest operating system (OSX) should already have Java installed. Older Macs may need to consult Apple’s Web site for additional help with Java. See http://www.apple.com/macosx/features/java/.

The enviromath Web site features two simple Java applets, one for exploring functions (FunctionLab) and the other for exploring difference equations (DifferenceEqLab). Both applets are free. They can be run on your browser "online," or downloaded to your computer and run locally or "offline". Both applets allow users to graph, trace, and create tables of values. The applets were written by our good friend Erik Neumann, who is also the author of myphysicslab.com. For information about the open source code for these applets, click here.The source code for these applets is covered by the GNU General Public License. Using the GNU GPL ensures that all subsequent improved versions will be free software. Here free means freedom rather than "no cost."

Our Web site also has a link to the Java applet StatCrunch, which is a comprehensive, statistical program. Among its many features, StatCrunch allows users to compute descriptive statistics and display data in many forms. StatCrunch users will need to register to create an account. The account allows users to save data and graphics onto the StatCrunch server. Beginning in August of 2006, there will be a small fee to obtain a StatCrunch account (academic site licenses available). StatCrunch was created by Webster West at the University of South Carolina. For more information, go to www.StatCrunch.com or read our brief Help for StatCrunch below.

Integrating the Applets with Quantitative Reasoning and the Environment                     top

The table below lists the topics in Quantitative Reasoning and the Environment which can be explored using applet technology. For more information on FunctionLab and DifferenceEqLab, see below. For more information, go to www.StatCrunch.com or read our brief Help for StatCrunch below.

Chapters

Topics

Applet

Chapters 1-3

Pie charts, bar graphs, histograms, scatterplots

StatCrunch

Chapters 4-6

Function tables and graphs
Regression and correlation

FunctionLab
StatCrunch

Chapters 7-10

Difference equations tables and graphs

DifferenceEqLab

Chapters 11-13

Histograms, boxplots, descriptive Statistics

StatCrunch

Help for FunctionLab and DifferenceEqLab                                                    top

1. Loading the applets
Go to the enviromath home page. Click on either FunctionLab or DifferenceEqLab.   A new Web page will open. While the Java applet is loading, you should see the Java logo displayed on your screen (see below).  

If the applet does not load, you may need to obtain the Java program. To get Java for Windows click here. Mac users should consult the Apple Web site (http://www.apple.com/macosx/features/java/).

2. Entering Functions and Difference Equations
FunctionLab allows users to plot up to four functions simultaneously.   All functions should be entered using the variable x.   Further syntax rules and function names can be found by pressing the HELP button on the FunctionLab applet.

DifferenceEqLab will plot up to three difference equations simultaneously. Difference equations must be written using n as the independent variable, and must be functions of the previous term(s) only. For example, the difference equation u(n) must be written in terms of u(n-1), v(n-1), and w(n-1). Additional syntax rules and function names can be found by pressing the HELP button on the DifferenceEqLab applet.

3. Downloading and running the applets locally
FunctionLab and DifferenceEqLab can be downloaded and run locally on a computer, rather than on an internet browser such as Internet Explorer, Firefox, or Mozilla.   By running the applets locally, it is not necessary to be connected to the internet.   Furthermore, the CopyGraph and CopyTable features on FunctionLab and DifferenceEqLab will be enabled. These features allow for easier copying and printing (see item 4 below).

To download FunctionLab, try one of the following links:
http://www.enviromath.com/graphlab/FunctionLab.jar
  
ftp://www.myphysicslab.com/graphlab/build/FunctionLab.jar
Save the file FunctionLab.jar to your computer or to a storage device. Be sure to remember where you saved the file. To run FunctionLab locally, locate the file FunctionLab.jar, and double-click to open the program. 

To download DifferenceEqLab, try one of the following links:
http://www.enviromath.com/graphlab/DifferenceEqLab.jar  
ftp://www.myphysicslab.com/graphlab/build/DifferenceEqLab.jar
Save the file DifferenceEqLab.jar to your computer or to a storage device. Be sure to remember where you saved the file. To run DifferenceEqLab locally, locate the file DifferenceEqLab.jar, and double-click to open the program.   

4. Copying and Printing Graphs and Tables
To print graphs and tables displayed in FunctionLab or DifferenceEqLab, we recommend copying the graph or table and pasting it into Word (or another word processor) and then printing from there. The procedures to copy and paste into Word are different if running the applets in a browser as opposed to locally on a computer (see item 3 above).   Below we outline the details.

Applets running in a browser:   To copy a graph or table displayed in FunctionLab or DifferenceEqLab, press the PrintScreen key on your keyboard. (On many keyboards, Printscreen is labeled “PrtScr,” or something like this. Also, you may need to hold down the Shift key while you press the PrintScreen key.) The PrintScreen key takes a “snapshot” of the entire computer screen. In Word, select Edit > Paste and the snapshot will be pasted into your document. From there you can crop the image so that only the graph or table remains (search Word’s help on cropping). Alternatively, obtain a program that takes a snapshot of any portion of your computer screen. One such program is MWSnap: http://www.mirekw.com/winfreeware/mwsnap.html.

Applets running locally:   If you downloaded FunctionLab or DifferenceEqLab to your computer (see item 3 above), the CopyGraph and CopyTable buttons will be active. Click on one of these buttons. In Word, select Edit > Paste and the graph or table values will be pasted into your document. For nicer formatting of tables, highlight the table values in Word and then select Table > Insert Table.

 

Help for StatCrunch                                         top

StatCrunch is a comprehensive statistical program written in the form of an online Java applet. Among its many features, StatCrunch allows users to compute descriptive statistics and display data in many forms. StatCrunch was created by Prof. Webster West at the University of South Carolina.

To get started with StatCrunch, go to www.statcrunch.com. If this is your first time using StatCrunch, you will need to create an account. Beginning in August 2006, there will be a small fee to obtain a StatCrunch account (academic site licenses available). Once you have an account, log in to StatCrunch using your account username and password.  

StatCrunch is quite intuitive to use, and offers drop-down menus and an extensive help menu. Running StatCrunch in a browser requires that users save their work often as a dropped internet connection will result in lost work! Users should also be aware that there is no “un-do” or “back” button on StatCrunch.

Below are a few basic directions to get started using StatCrunch with Quantitative Reasoning and the Environment.

Entering Data: Click on the first cell at the top of a column. The cell will turn light blue. Type in a number or word, and press Enter or Return on your keyboard. The next cell below will turn blue. Continue entering data in this fashion.

Changing the Column Header: StatCrunch columns are named var1, var2, and so on. To change the column header, click on the header and then press Delete or Backspace on your keyboard. Type in the new name.

Saving Data: Select Data > Save data. Enter a name for your data set. Select a delimiter (“space” will often work fine). Your data will be saved to your StatCrunch account.

Clearing Data: To erase one entry in a column, click on the cell and press the Backspace key. To erase a single column of data, select Data > Data table > Delete columns. A small window will appear. Click on the column name; then, select Delete. To erase all data, select Data > Data Table > Clear.

Loading Data: To load one of your previously-saved data sets, select My Data in the upper right-hand corner of StatCrunch. Click on the data set’s name to load it into StatCrunch. To load data from the enviromath website (see Chapter Projects and Chapter Data Sets), click on the orange StatCrunch button and the data will load automatically.

Sorting Data: To sort a column of data, select Data > Sort columns. A new window will appear. Click on the column name then select Sort Column. A new column will be created listed the sorted data. It is sometimes helpful to delete the column of unsorted data, and rename the new sorted column. But beware! Once data is deleted, it cannot be retrieved.

Computing 1-Variable Statistics: To compute 1-Variable statistics (mean, median, Q1, etc.) for a single column of data, select Stat > Summary Stats > Columns. A small window will appear. Select the column name then click on Next. A new window will appear in which all of the statistics names are selected; deselect some if you wish. Then click Calculate.

Computing and Graphing a Linear Regression Equation: Enter the (x, y) data into two columns, then select Stat > Regression > Simple Linear. A window will appear. Select the appropriate column for X-Variable and Y-Variable, press Next and then Next again. In the new window select “Plot the fitted line,” select Next, and then select Calculate. A new window will appear that lists the best fitting equation and correlation coefficient. By pressing Next the graph will be displayed.

Computing an Exponential Regression Equation: Enter the (x, y) data into two columns. Take the logarithms of the y-values by selecting Data > Transform data. A new window will appear. Select the Y column. Under Functions select log(Y) then press the Set Transformation button. Finally, press the Transform button and a new column of transformed y-values will appear.

It is now necessary to compute the linear regression through the (x, log(y)) data. Select Stat > Regression > Simple Linear. A window will appear. Select the columns for the X-Variable and Y-Variable. For the Y-variable, be sure to select the transformed column. Select Calculate and a new window will appear that lists the linear regression through the transformed (x, log(y)) data as well as the correlation coefficient. The line will be in the form log(y) = mx + b.

To obtain the exponential regression equation of the form y = y0M^x, use the formulas y0 = 10^b and M = 10^m. For further details, consult Chapter 5 in the text.

Computing a Power-Law Regression Equation: Enter the (x, y) data into two columns. Take the logarithms of the x-values by selecting Data > Transform data. A new window will appear. Select the X column. In the Transformation bar at the top, enter log(“x-variable name”). For example, if the X column is titled pounds, enter log(“pounds”). Press the Transform button and a new column of transformed x-values will appear. Take the logarithms of the y-values by selecting Data > Transform data. A new window will appear. Select the Y column. Under Functions select log(Y) then press “Set Transformation.” Press the Transform button and a new column of transformed y-values will appear.

It is now necessary to compute the linear regression through the (log(x), log(y)) data. Select Stat > Regression > Simple Linear. A window will appear. Select the columns for the X-Variable and Y-Variable. Be sure to select the transformed columns for both variables. Select Calculate and a new window will appear that lists the linear regression through the transformed (log(x), log(y)) data as well as the correlation coefficient. The line will be in the form log(y) = mlog(x) + b.

To obtain the power-law regression equation of the form y = kx^c, use the formulas k = 10^b and c = m. For further details, consult Chapter 6 in the text.

Pie Charts and Bar Charts: Enter the categories into a single column and the correspond values (“counts”) into a second column. Select Graphics > Pie Chart or Bar Chart > with summary. A window will appear. Select the appropriate columns for “Categories in” and “Counts in.” Peruse graph options by selecting the Next buttons. Finally press Create Graph!

Histograms and Boxplots: To create a histogram or boxplot for a single column of numerical data, select Graphics > Histogram or Boxplot. A new window will appear. Select the column name. Press Next to set graph options. Finally, press Create Graph!

Scatter Plots and Line Graphs:  Enter the (x, y) data into two columns. Select Graphics > Scatter Plot. A new window will appear. Select the columns for the X and Y variables. Press Next to set graph options (under display, select “Lines” for Line Graphs). Finally, press Create Graph!

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