The movable linear fit is used to manually draw a linear regression over the selected area of a graph and display the slope (m) and y-intercept (b) of that line. It is available in Logger Pro 3.8.4 or newer.

Complete the following steps to perform a movable linear fit:

  1. Click and drag across a region of interest. The shaded area contains the selected data upon which the movable linear fit will be calculated. If a region is not selected, the movable linear fit will be calculated for all data displayed in the graph.
  2. Choose Model from the Analyze menu and choose the equation type Linear. A helper object containing the slope, y-intercept, and RMSE of the line will be added to the graph.
  3. Double-click the helper object and select the Enable Line Drag option.
    The movable linear fit can now be adjusted by dragging one of the three handles on the line. The center handle adjusts the Y-intercept and the outer two handles can be used to rotate the line about the far edge. If the X axis is scaled from zero, then the right handle will control the slope while leaving the Y-intercept alone.
  4. To remove the movable linear fit, click the X in the upper corner of the helper object.

You may want to perform a normal linear fit using Logger Pro before you use this feature. Enter the slope and intercept values from the fit from Logger Pro into the model. You can then move this new linear fit and will still be able to see the standard linear fit with it.