Change from Baseline



Good Morning,
Let's say I am looking at number of sneezes over a course of a month and I want to calculate the Percent Change from Baseline in Sneezes per Week.

My first idea would be to do so using the following formula:
1-(Change in Sneezes per Week/Number of Sneezes per Week at Baseline)*100

However, is someone had 0 sneezes at their baseline week, then this formula does not work.

What should I do?

Thank You!!
Well, certainly you can't calculate a percentage of 0.

Do you have to calculate % change from baseline? If not, you might thing about looking at changes in the rate of sneezing from one week to the next (or over the course of a number of weeks).