Residuals and Intensity Residuals Window

These produce plots to assess the quality of a fit. There many possible forms for the plots, and in fact two possible residuals windows:

• The standard residuals window, where the observed and calculated values from the current fit are plotted. This is appropriate for all fits.
  
• The intensity residuals window, where the observed and calculated values are always intensities of the fitted lines, even if the current fit is not to intensities. This requires intensity information to be present in the fit input, and is particularly suitable for Automatic Fitting.

These will normally appear automatically when relevant, but can be shown with "View","Residuals" and "View","Intensity Residuals". The default residuals window will look something like this:

The status bar displays the x, y co-ordinates of the mouse and, if the mouse is over an experimental point, the source of the data point. Right click on the point for various options for working on observations; see below for a list. If you select an area with a mouse additional options applying to the points inside or outside the area are available.

If PGOPHER is correctly configured, you can go directly to the source of the data by right clicking on a given point and selecting "Edit Point" - see below for other options.

For the formulae below, o_i is the ith observation, c_i the corresponding calculated value, p_i is a population and w_i the weight. The population, p_i, is the calculated population of the upper or lower state, depending on the setting of the Upper check box. The average error displayed at the top is simply [Σ[(o_i-c_i)/w_i]²/n_obs]^½, which is slightly different to the value given in fits as it does not take account of the number of parameters floated. (This allows a value to be calculated without doing a fit.)