FAST 4.02-01 Use well-defined format styles
Make use of well-defined format styles, ideally merged from a standard workbook that has pre-built styles that are well-engineered and with which the modeller is familiar. Do not lazily stay with the simple defaults provided with Excel.
FAST 4.02-02 Do not merge cells
Avoid merge cell alignment setting, as it disrupts ability to select columns efficiently. (As well, it is rarely of great benefit with advent of Excel’s center-across-selection setting.) Merging cells is one of those options that seems like a good idea at the time but then turns out not to be. From a first principles perspective, merging cells breaks the only element of inherent structure that Excel starts with and that doesn’t have to be imposed by the modeller. That doesn’t seem like it would get us off to a good start from a ‘consistency of structure’ perspective. Selecting columns and/or rows gets confused when models have cells merged across them and unmerging is time consuming and can cause referencing problems.
The latter is the most common problem faced by modellers in relation to merging cells. However, other points which should be noted while dealing with merge cells are:
- Dealing with merge cells in macros can be very problematic.
- Model review or audit software also struggles with merged cells and may sometimes simply unmerge all cells in the process of running their analysis procedures.
- When a selection of cells containing multiple data values are merged into one cell, then only the upper-left most data value is kept and rest are deleted; unmerging these cells will not bring back those initial cell values.
The only advantage which ‘merge cells’ options provide in a financial model is the formatting and graphical representation to the summary tables, key output and representation sheets, etc. However, when this benefit can be achieved by using center-across-selection cell formatting, there is no reason at all to use the merge cells in financial models.
