Graphical Analysis Program (a "Demo Copy" can be obtained for home use by going to http://www.vernier.com/downloads/index.html )

A. Entering and Graphing Data

1. If you are manually entering data, open Graphical Analysis: (at school you will click the start button--- Physics Programs--- Graphical Analysis)
2. Click in the box beside Row 1 in the X column and type in the X-value of the first data pair. Press [ENTER] which will take you to the Y column in Row 1. Type in the Y-value for the first data pair. Press [ENTER] which takes you to Row 2. Enter the rest of the data in a similar manner. As the data pairs are entered, they will be shown on the graph.
3. If you need to change a value, click on the box containing the data, which will become highlighted, and type in the new value. Press [ENTER] after making the correction.
4. You do not want the points connected by a line, double click in the graph window. Deselect Connecting Line under the Graph menu.
5. Double Click on the X column header. Enter the New Name and the New Units. If needed you can set the Dec. Places in the Rounding box to desired value. Click OK. The label and units automatically appear on the graph.
6. Double Click on the Y column header. Enter the New Name and the New Units. If needed you can set the Dec. Places in the Rounding box to desired value. Click OK. The label and units automatically appear on the graph.
7. To get a linear regression line on the graph, click and drag over the region of the graph to be analyzed and select Regression under the Analyze menu (note sometimes the data is selected by default and you do not have to select it). The slope, y-intercept, and correlation factor will be displayed. To close this display, click on the tiny x close box in the regression statistics box. Determine if your graph is linear. (visual inspection, correlation, meaning of y-intercept).  If the graph is not linear, but looks mathematical, determine if the graph can be "linear-zed" (i.e. does it look like one of the graphs on your reference sheet).  If it can be linearized then follow the instructions below to make a new column.  If it can not then do an "Automatic Curve Fit", see section Bof this sheet.
8. To create a new column in which data is calculated, click on the data set. Select New Column under the Data menu. Select Calculated. It will allow you to enter a New Column Name and New Column Units and a Formula for the new column. The new formula should be generated using the  Columns button. Click OK when you have done this.
9. To change the column of data graphed on a given axis, click on the label for that axis. A dialog box will appear that will allow you to select from any of the columns of data. Be sure to select only one box for each axis. Click OK when you have done this. ( This can also be done using the X-Column and Y-Column Options under the Graph menu.)

B. Curve Fitting

1. One way to determine the relationship between two variables is to modify the variables until you get a linear relationship. Another way is to try to fit various functions to your data and see which curve fits best. If your data can be linearized then do so, however some relationships (like quadratics and trig functions) can not be linear-ized, in these cases you will have to use the Automatic Curve fit.
2. Automatic Curve Fit under the Analyze menu offers a list of standard functions to try as well as the ability to enter other functions. Select from the stock functions or type in a function and click OK. The trial fit will appear on the graph and the function, constants, exponents, and mean square error will appear below the graph. A low value for the mean square error indicates a good fit. Click on OK-Keep Fit if the fit is fine. The curve will appear on the graph and the function, constants, exponents, and mean square error will appear on the graph. If the fit is not good, click on the button Try New Fit to try other functions.
3. You can try a manual fit to a function which allows you to try different starting values for the constants and exponents in that function. Manual Curve Fit under the Analyze menu offers a list of standard functions Select from the stock functions or type in a fucntion and click OK. Enter starting values for the constants and exponents. A curve will appear that may not pass through the points. Change the constants and exponents to try to get the curve to pass through the points and get a lower mean square error. Click on OK-Keep Fit when the fit is fine.

C. Printing and Saving

1. Go to Print Setup under the File menu. Click on the Setup box and click on Landscape to print the graph down the page. Click on OK to close the two print setup windows. Go to the File menu and select Print and then select Print .
2. Go to the File menu and select  Print Data Set or Print Graph. Since each data set may contain a large amount of data and will take a large amount of paper to print all the data sets. You may be told to only print the Graph.
3. Note:  The printer in our room ALWAYS thinks it is out of paper--- it will beep and the screen will say it is out of paper--- mot of the time it isn't.  When you print a member of you lab group needs to go to the printer and HIT THE GREEN BUTTON when the printer beeps, you will have to hit the green button for each page that you print.
4. Data can be saved under the File menu. Use Save As under the File menu to save the data your S drive. It will ask you for a name for the file.

D. Extras if needed:

1. To change the scale on a given axis, click on the label for that axis. A dialog box will appear that will allow you to select from Autoscale from 0, Autoscale, or Manual Scaling entering the limits for the axis. Click OK when you have done this. You can also manually scale the axes by clicking on the number at the end of each axis and typing in a new value. Press [ENTER] after typing in the value. 
2. To find the coordinates of each data point, select Examine under the Analyze menu. As you move the cursor, the coordinates of each point will be displayed. Deselect this to turn this feature off.
3. To find the slope of the tangent to the curve at each data point, select Tangent under the Analyze menu. As you move the cursor, the slope of the tangent each point will be displayed. Deselect this to turn this feature off.
4. To display statistics about your data ( mean, standard deviation, minimum, maximum), click and drag over the region of the graph to be analyzed and select Statistics under the Analyze menu. To cut off this display, click on the close box in the statistics information box.
5. To integrate the area under a region of your graph, click and drag over the region of the graph to be analyzed and select Integral under the Analyze menu. The area under the curve will be displayed. To cut off this display, click on the close box in the integral information box.