Calculating the weighted average

[Johannes_Strobe]

Hello,

how can I calculate the weighted average? 

Example:
[-4, 0, 2, 0] -> I get this values via a roolup
I want the result to be -2 i.g.. Correct me please if I am wrong.

I'm open to use multiple formulas.

Best regards
Johannes

[stevendasilva · Accepted solution]

@Johannes_Strobe 

Just to confirm are you looking for the average but only if the result is not 0? 

If yes this has been solved over here:
https://community.airtable.com/t5/formulas/excluding-zero-values-from-an-average-rollup/td-p/26312

[Johannes_Strobe]

Hi @stevendasilva ,

thanks. I already saw the post. While reading the message more closely, I found out that it actually is the solution for my problem. However, there is no example, so I didn't figure it out the first time.

My solution was to return BLANK() instead of a 0, when the Formula encountered a BLANK() at the first or second value. If this is done, the AVERAGE() function of the Rollup skips these values.

Example:

• Values is the first table:
  • Data: The data are either blanks or numbers from 1 to infinite. They represent "bad" and "good" occurrences. 
  • Formula: IF(AND({👍}=BLANK(), {👎}=BLANK()), BLANK(), IF({👍}=BLANK(),-{👎},IF({👎}=BLANK(),{👍},{👍}/({👎}+{👍}))))
  •  
• Rollup in the other table: IF(COUNTA(values)!=0, AVERAGE(values), BLANK())

Best regards

Johannes

[stevendasilva]

@Johannes_Strobe  Awesome, nice work.