Graphing Tutorial: Line Graphs Walkthrough

Line graphs are used when the independent variable is represented by a numerical sequence (1, 2, 3…) rather than discrete categories (red, yellow, blue…). [Note: The dependent variable is always a numerical sequence.]

1. Click the green boxes to open text boxes for your title and labels.
2. Once you’ve entered all three labels, gray squares will appear at both ends of the x and y axes. Click these to open text boxes for your minimum and maximum values.
   • TIP:Look carefully at the table with the dates and dissolved oxygen mg/l. For the minimum x value, choose a date just before the earliest one in the table, and for the maximum x value, choose a date just after the latest one in the table. Similarly, for the y axis, choose values below the lowest dissolved oxygen mg/l measurement and above the highest.
   • TIP: Dates must be entered in the format mm/dd/yyyy. You’ll need to enter the slashes.
3. Once you’ve chosen your minimum and maximum values, intermediate values will appear automatically. These dates and numbers may not match those in your table. That just means your plot points will fall between them.
4. Text boxes will appear for you to enter your x values and y values. Remember that dates must be entered in the format mm/dd/yyyy. Press the ‘Next’ button and a red dot will appear in the location you entered on the graph.
   • TIP: The ‘Clear’ button will clear your entire graph.
   • TIP: The ‘Draw Line’ button will work as soon as you have two points. You can add more points and redraw the line.