Calculating percent chagne over time, based on first value

Question

Hello, I'm trying to create a percent increase measure over time. So basically I've got items that have amounts tied to them and dates the transactions happened
example data

• Item: 004502, Amount: 10, Date: 1/1/2020
• Item: 004502, Amount: 15, Date: 1/15/2020
• Item: 004502, Amount: 20, Date: 1/30/2020
• • Item: 004502, Amount: 8, Date: 2/5/2020

I'm going to use this measure to graph percent increase over the time frame. We want the values at each point to compare with the first value, rather than the previous value. So for example on 1/15 the percent increase would be 50%. And on 1/30 it would be 100%, on 2/5 it would be -20%

The way the report is set, the original date needs to be dynamic. The user is able to change what the start date is so if they put in 1/1/2020 then the above example would apply. However, if they put in 1/10/2020; then the first transaction would be the one on the 15th. So the percent increase that shows on 1/30 would then be 33% and on 2/5 it would be -46.67%.

Any help on accomplishing this would be greatly appreciated.

Thanks!

Answer 1

Hi,
Are we talking about a Multidimensional Model or Tabular Model?
Are you using MDX or DAX query? What specific error did you meet?