Small inconsistencies in the numbers of your presentation (28 or 27 portfolio companies, 27 or 28 investments?) can confuse the audience (they are trying to figure out the numbers instead of listening to your story and evaporate your credibility (if that number is wrong, what about the others?).
Most of the time, what looks like small mistakes aren’t actually mistakes, just different cuts of the numbers (including follow up rounds, excluding Ireland, first 9 months instead of half year, rounding, etc. etc.). The analyst can easily defend them and nobody did anything wrong.
But, these “mistakes” are a pain. How do you prevent them?
Create one very simple spreadsheet with the top line numbers that is the source for every slide in the deck, and in case your presentation derails into an argument about data, put in that spreadsheet in the appendix to kill these discussions in a second.
This all sounds very easy and obvious, but think about it next time, someone makes a direct edit in a column chart from the top of her mind (“hmmm, that 27 should be 28”).