If your browser has an Excel plug in or if you have Excel you can use this spreadsheet to do a least squares linear regression for your lab data.
LEFT click on the following link to use the spreadsheet directly in the browser (if it does not show up then you don't have the Excel plug in). NOTE: Some functions do not work in the browser version. OR: RIGHT click on the following link and save the Excel spreadsheet to a convinient location on your hard drive: Regression Spreadsheet.
Change the numbers in column A to be your horizontal (x-axis) data. Change the numbers in column B to be your vertical (y-axis) data. Click in the 'Plot Area' once to activate the colored data area boxes (surrounding your data). Place the cursor over the lower right corner of the data box and re-size the box to include only your data (pull it down if you have more than 10 pairs of points, pull it up if you have less than 10 pairs). Click on the labels (Time, Location or Regression) once to activate the box and then again to insert the cursor. Change the labels to say what you want them to say. Click on the 'Plot Area' one more time to update all the values and to select the area you want to print. Choose 'Print' from the file menu to print the graph. NOTE: If you have the worksheet selected instead of the 'Plot Area' you will get a printout of your data instead of the graph. The regression line y = Mx + B should be showing on the graph with the correct slope (M) and y-intercept (B) values inserted (you will need these for your report).
You can change the style, font, font size, etc. of the numbers along the x or y axis by double clicking on them. A box will come allowing you to change how the numbers appear on the graph. If you double click on a data point you can change the symbol and symbol color of the plotted data. If you double click on the regression line you can change what the line looks like (thickness, color, etc.).