The Total Cost Model 1.8 is here…

While some much-needed fixes were added to version 1.5 to make the Total Cost Model 1.6 more user-friendly and functional, work on the newest version, 1.8 (4.10.23), is now complete. It includes more spelling fixes, more error handling, and less code clutter plus a few new features to make things easier. Hundreds of bug fixes and code improvements make this version more stable and error-free.

Testing and the final code “brush-up” for version 1.8 took longer than expected. Several show-stopper bugs paused the release, but better that I find them than you. Most of the fixes, enhancements, and new features are described below.

New User Guide

Work was finished on the new Total Cost Model User Guide. It was written for use by anyone trying to understand the workbook, not just financial gurus. Previously all the user information came from the 2004 paper “The Economics of Open Source Software, A Model for Total Cost Analysis“. Now an up-to-date PDF guide is included in the Version 1.8 archive which can be downloaded here.

The manual contains 25 pages of descriptions, explanations, and directions which should leave no questions about the utility of the Model. Additionally, the Guide contains many screenshots and several tables for enhanced readability.

New features and fixes

The Options form received much of the updating, it now has 4 more selectable items. They address hiding (or unhiding) Excel’s comments which are used as a “pop-up” help on the worksheets and the visibility of the “hidden” columns. In the following image, they are the 4 options at the end of the list of checkboxes.

The Updated and Improved Options form

I usually tend to hide columns that store variables and provide additional calculations. Using hidden cells for calculations helps shorten the length of my formulas and reduces their complexity. The ones on the Total Cost Model may actually help you to understand the relationship between the cost factors. So it is now your choice to hide or not to hide. There are no secrets there…

Cost Analysis worksheet showing the “hidden” columns at the right

The PayBack function switcher…

Because there is more than one way to calculate the Simple and Discounted Payback metrics, a new function “chooser” form has been added (shown in the following image.) To open the switcher form simply go to the Options form and click the “Payback Method” button at the bottom of the page. From there you will have the choice of three Payback functions, each calculates differently They are plainly explained on the form.

The Payback Switcher form

What else is new…

Some of the other additions included in version 1.8 of the Total Cost Model are:

  • More error handlers and fixes to make the existing handlers more informative and robust.
  • Over 100 specific bug fixes…some minor, but many major (even a few Show Stoppers!)
  • Spelling and user interface corrections.
  • The Concepts and Instructions worksheet has been updated with new graphics and text.
  • Removal of unused Document Properties and some marginal global variables.
  • Several globally used variables and properties have been moved to cells in the hidden columns on the Common Data worksheet for easier inspection, processing, and maintenance.
  • Modular-level variables have been given the prefix “m_” to show their scope.
  • The remaining Global level variables have been given the prefix “g_” to show their scope.
  • The Data Wizard (used for creating new models or editing existing ones) has been reworked and includes many fixes and several new features. A Reset button now allows you to return to the original data BEFORE you insert it into the model.
  • Data entry error correction on both the Common Data worksheet and The Alternative Systems costs worksheets has been significantly improved.
  • The Data Wizard also received some error correction love and seems to be quite stable now while keeping an eye on inputting correct data into your model.
  • Many local variables have been removed. Some were left over from “dead code.”
  • Numerous code enhancements.
  • …and much code cleanup…

As usual, you will be able to get the new Total Cost Model from its homepage.