I have a daily dataset that on a regular basis don't change at all, however when the percentage of "CapitalPercent" between days are changing I want it to be flagged somehow. I was thinking about creating a measure that will check the daily dataset and compare it to the day before and if something got changed then it will notify the user.
The tweak you've suggested resulted in that if previousday of a specific date is BLANK then provide the VAR sumQuantity. However, this is not really the case. When the previousday is blank you need to compare the value to the last value that was given and look for a change there.
You suggestion is a good start to facilitate the requirement but is not complete.