Graphical Analysis^TM

Changing Graph Options

BHS -> Staff -> Mr. Stanbrough ->GA How-To Notes -> this page

The graph options dialog is show above. Some of the commonly used options are:

• Point Size - This is largely a matter of preference, however, if you don't use point protectors, you should probably use Large Points.
• AutoScale:
  • Scale from Data means that the program will automatically scale the graph so that the data points are all visible in the graph, and so that the data points fill the graph.
  • Scale from 0 means that the axes origin will always appear in the graph.
• Selected Data Sets: Displays a menu of all data sets you have entered. You can select one or more data sets to appear in a graph. In the screen shot shown above, bot Data Set 1 and Data Set 2 will be displayed in the (same) graph.
• Graph Style:
  • Point Protectors are small symbols (squares, rectangles, circles, etc.) that appear around data points that make them easy to find on the graph and also identify which data set they belong to. This option can also be selected/deselected from the Graph Menu.
  • Error Bars graphically indicate the estimated uncertainty of the data points. This option can also be selected/deselected from the Graph Menu.
  • Connecting Lines are the "connect the dots" type of graph that you NEVER, NEVER, NEVER draw in Physics class.
  • Bar Graph displays the data in bar graph form. This is of limited usefullness in Physics. (See Bar Width.) This option can also be selected/deselected from the Graph Menu.
  • Background Grid turns the "graph paper" background on and off. This option can also be selected/deselected from the Graph Menu.
  • Legend displays a small chart identifying the point protectors of the various data sets displayed in a graph. This option can also be selected/deselected from the Graph Menu.
  • Regression Line displays the "best straight line" that fits the current data. It of course, is only useful if the quantities being graphed have a linear relationship. (If the relationship is not linear try a curve fit.) This option can also be selected/deselected from the Graph Menu.
  • Regression Statistics displays the slope, y-intercept, and the corelation coefficient for the best fit regression line. A corelation coefficient of 1 means that all data points perfectly fit a straight line of positive slope. A corelation coefficient of -1 means that all data points perfectly fit a straight line of negative slope. Therefore, if the absolute value of the corelation coefficient is close to 1, it means "good fit for a straight line". This option can also be selected/deselected from the Graph Menu.
• Bar Width refers to the width of the bars drawn for a bar graph.
• Error Bar Size: You can specify the size of the horizontal and vertical error bars. If the "Percent" box is checked, then the number entered in the field is considered to be a relative uncertainty, otherwise, it is considered to be an absolute uncertainty.
• Use Preferences overrides the current graph options settings.