Our treatment of engineering economy up to this point has ignored the possibility of uncertainty in various parameters that we have dealt with while analyzing the economics of projects.  For example, we have ignored completely the uncertainties associated with, among other things, future sales volumes, prices, and salvage values.  But we know that predictions of future values of these variables will most likely be incorrect.   So, the point estimates that we have been working with will need to be replaced by range or interval estimates.  And we will need to associate appropriate variability measures to the estimates of the most likely values of the variables that we use in our analysis.  Chapter 14 deals with these issues; Appendix B extends this concept to using the computer to simulate the economic behavior of the real world for evaluation purposes.  In this course, however, Appendix B is not included.  Section 14.5 from Chapter 14 is also not a part of this course.