Problem caluclating the average

Question

Hi,
The requirement is as follows:
Col A | Col B
1 | 4.1
1 | 3.2
1 | 1.1
1 | 2.3
1 | 1.5
2 | .3
2 | 6
3 | 0.2
3 | 8
3 | 3.1
and so on....
I need Column C that calculates the average of each group of Column A (Ex:- (4.1+3.2+1.1+2.3+1.5)/count(1's in col A)), (0.3+6)/count(2's in col A), etc. and I was able to achieve that creating a new column in the report and writing in it the below formula as below:
sum("Col B")/count("Col A")
The result was as follows which is correct:
Col A | Col C
1 | 2.46
2 | 3.15
Now my next task is to find the average of the above like sum(Col C)/count(Col A). I tried to calculate the same using the below formula
sum(sum("Col B")/count("Col A"))/count("Col A")
but the average is somehow not being calculated correctly when i try to validate using manual calculation. I changed the column properties to decimals upto 4 places, I even tried with 8 places of decimal, but still the answer is not correct. What am I doing wrong, is the above formula correct?
Appreciate your quick response and help. Thanks!!!!!

Answer 1

Pankaj wrote:
Hi,
The requirement is as follows:
Col A | Col B
1 | 4.1
1 | 3.2
1 | 1.1
1 | 2.3
1 | 1.5
2 | .3
2 | 6
3 | 0.2
3 | 8
3 | 3.1
and so on....
I need Column C that calculates the average of each group of Column A (Ex:- (4.1+3.2+1.1+2.3+1.5)/count(1's in col A)), (0.3+6)/count(2's in col A), etc. and I was able to achieve that creating a new column in the report and writing in it the below formula as below:
sum("Col B")/count("Col A")
The result was as follows which is correct:
Col A | Col C
1 | 2.46
2 | 3.15
Now my next task is to find the average of the above like sum(Col C)/count(Col A). I tried to calculate the same using the below formula
sum(sum("Col B")/count("Col A"))/count("Col A")
but the average is somehow not being calculated correctly when i try to validate using manual calculation. I changed the column properties to decimals upto 4 places, I even tried with 8 places of decimal, but still the answer is not correct. What am I doing wrong, is the above formula correct?
Appreciate your quick response and help. Thanks!!!!!First of all, using your figures as actual examples, the average for 1 is not 2.46, but 2.44.
To get what you are looking for, do this:
1) To get the average of each group in Col A, use this formula in a column called "Average":
AVG(Col B BY Col B)
Use a pivot table and put Col A in the Rows Section and the Average column in the Measures Section. Don't put any other columns in this pivot table or you will get unexpected slicing and dicing of the data.
2) To get the average of the averages, duplicate the pivot table to get Pivot Table:2 and put the "Average" column in the Measures Section. Exclude all other columns. (In other words, take out column A from the Rows Section. You will get the average of the averages.