Quantitative Stratigraphy, Splining and Geologic Time Scales - Geomathematics: Theoretical Foundations, Applications and Future Developments - page 342

Fig. 9.26 Example of CASC multi-well comparison with three types of error bars. The probable
positions of the time-lines were obtained from event-depth curves fitted to the biostratigraphic
information of individual wells (Source: Agterberg 1990 , Fig. 1.2)
obtained by collecting deviations between observed and probable positions for all
events from within the subsets of wells in which the events were observed to occur.
The standard deviations of these distributions can be used to distinguish between
good and bad marker events. All deviations between observed and estimated
positions are small for good markers. Lines of correlation connecting two good
markers in different wells generally do not cross each other unless the two events