Average calculation












0












$begingroup$


I know it will be a stupid question for somebody but I need to understand.



Below the matrix:
$$ left[
begin{array}{cc|c}
55&0&0\
55&0&0\
15&8&53\
15&4&27\
10&2&20\
10&2&20
end{array}
right] $$



The 1st column is the target, the 2nd is the actual and the 3rd is the percent achievment
$text{round} left(frac{text {actual} cdot 100}{text{target}} right)$



The question is:

Why I cannot calculate an average on the $3^{text {rd}}$ column ?



Why do I have to use this formula :
$$frac{sum{ text {actual}}*100}{sum{ text {target}}}$$



The result is $$ left[
begin{array}{cc|c}
160&16&10
end{array}
right] $$



and not $$ left[
begin{array}{cc|c}
160&16&20
end{array}
right] $$










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    I think the mistake you made is to assume that $$ frac{sum text{actual}}{sum text{target}} = sum frac{text{actual}}{text{target}} $$ Which is not true.
    $endgroup$
    – Matti P.
    Jan 25 at 9:50












  • $begingroup$
    You well summarized my mistake
    $endgroup$
    – Paul
    Jan 25 at 18:27
















0












$begingroup$


I know it will be a stupid question for somebody but I need to understand.



Below the matrix:
$$ left[
begin{array}{cc|c}
55&0&0\
55&0&0\
15&8&53\
15&4&27\
10&2&20\
10&2&20
end{array}
right] $$



The 1st column is the target, the 2nd is the actual and the 3rd is the percent achievment
$text{round} left(frac{text {actual} cdot 100}{text{target}} right)$



The question is:

Why I cannot calculate an average on the $3^{text {rd}}$ column ?



Why do I have to use this formula :
$$frac{sum{ text {actual}}*100}{sum{ text {target}}}$$



The result is $$ left[
begin{array}{cc|c}
160&16&10
end{array}
right] $$



and not $$ left[
begin{array}{cc|c}
160&16&20
end{array}
right] $$










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    I think the mistake you made is to assume that $$ frac{sum text{actual}}{sum text{target}} = sum frac{text{actual}}{text{target}} $$ Which is not true.
    $endgroup$
    – Matti P.
    Jan 25 at 9:50












  • $begingroup$
    You well summarized my mistake
    $endgroup$
    – Paul
    Jan 25 at 18:27














0












0








0





$begingroup$


I know it will be a stupid question for somebody but I need to understand.



Below the matrix:
$$ left[
begin{array}{cc|c}
55&0&0\
55&0&0\
15&8&53\
15&4&27\
10&2&20\
10&2&20
end{array}
right] $$



The 1st column is the target, the 2nd is the actual and the 3rd is the percent achievment
$text{round} left(frac{text {actual} cdot 100}{text{target}} right)$



The question is:

Why I cannot calculate an average on the $3^{text {rd}}$ column ?



Why do I have to use this formula :
$$frac{sum{ text {actual}}*100}{sum{ text {target}}}$$



The result is $$ left[
begin{array}{cc|c}
160&16&10
end{array}
right] $$



and not $$ left[
begin{array}{cc|c}
160&16&20
end{array}
right] $$










share|cite|improve this question











$endgroup$




I know it will be a stupid question for somebody but I need to understand.



Below the matrix:
$$ left[
begin{array}{cc|c}
55&0&0\
55&0&0\
15&8&53\
15&4&27\
10&2&20\
10&2&20
end{array}
right] $$



The 1st column is the target, the 2nd is the actual and the 3rd is the percent achievment
$text{round} left(frac{text {actual} cdot 100}{text{target}} right)$



The question is:

Why I cannot calculate an average on the $3^{text {rd}}$ column ?



Why do I have to use this formula :
$$frac{sum{ text {actual}}*100}{sum{ text {target}}}$$



The result is $$ left[
begin{array}{cc|c}
160&16&10
end{array}
right] $$



and not $$ left[
begin{array}{cc|c}
160&16&20
end{array}
right] $$







average percentages






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 25 at 9:57









Mohammad Zuhair Khan

1,6742625




1,6742625










asked Jan 25 at 9:44









PaulPaul

31




31








  • 1




    $begingroup$
    I think the mistake you made is to assume that $$ frac{sum text{actual}}{sum text{target}} = sum frac{text{actual}}{text{target}} $$ Which is not true.
    $endgroup$
    – Matti P.
    Jan 25 at 9:50












  • $begingroup$
    You well summarized my mistake
    $endgroup$
    – Paul
    Jan 25 at 18:27














  • 1




    $begingroup$
    I think the mistake you made is to assume that $$ frac{sum text{actual}}{sum text{target}} = sum frac{text{actual}}{text{target}} $$ Which is not true.
    $endgroup$
    – Matti P.
    Jan 25 at 9:50












  • $begingroup$
    You well summarized my mistake
    $endgroup$
    – Paul
    Jan 25 at 18:27








1




1




$begingroup$
I think the mistake you made is to assume that $$ frac{sum text{actual}}{sum text{target}} = sum frac{text{actual}}{text{target}} $$ Which is not true.
$endgroup$
– Matti P.
Jan 25 at 9:50






$begingroup$
I think the mistake you made is to assume that $$ frac{sum text{actual}}{sum text{target}} = sum frac{text{actual}}{text{target}} $$ Which is not true.
$endgroup$
– Matti P.
Jan 25 at 9:50














$begingroup$
You well summarized my mistake
$endgroup$
– Paul
Jan 25 at 18:27




$begingroup$
You well summarized my mistake
$endgroup$
– Paul
Jan 25 at 18:27










1 Answer
1






active

oldest

votes


















1












$begingroup$

Intuitively, this is because your target have different values, they have different "weights/importance" into your total target.



Imagine an extreme case, where you add another very high target : 1,000,000 for instance, and suppose you actually reach 0 on this target. The percentage of achievement for this task is 0, and overall you should be very close to 0% of total achievement. The other targets almost don't count compared to the new main one.



But if you compute the average directly on the percentage of achievement, then you suppose that the new task counts as much as the old one, only reducing the total achievement percentage by 1/7th.



In short : They are two possible goals. You should:




  • recalculate the total average from the total actual divided by total target if you want to know the average achievement of the total target


  • average on percentage of achievements if you want to know the average achievement of the different tasks, giving each task the same importance.







share|cite|improve this answer









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    1












    $begingroup$

    Intuitively, this is because your target have different values, they have different "weights/importance" into your total target.



    Imagine an extreme case, where you add another very high target : 1,000,000 for instance, and suppose you actually reach 0 on this target. The percentage of achievement for this task is 0, and overall you should be very close to 0% of total achievement. The other targets almost don't count compared to the new main one.



    But if you compute the average directly on the percentage of achievement, then you suppose that the new task counts as much as the old one, only reducing the total achievement percentage by 1/7th.



    In short : They are two possible goals. You should:




    • recalculate the total average from the total actual divided by total target if you want to know the average achievement of the total target


    • average on percentage of achievements if you want to know the average achievement of the different tasks, giving each task the same importance.







    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      Intuitively, this is because your target have different values, they have different "weights/importance" into your total target.



      Imagine an extreme case, where you add another very high target : 1,000,000 for instance, and suppose you actually reach 0 on this target. The percentage of achievement for this task is 0, and overall you should be very close to 0% of total achievement. The other targets almost don't count compared to the new main one.



      But if you compute the average directly on the percentage of achievement, then you suppose that the new task counts as much as the old one, only reducing the total achievement percentage by 1/7th.



      In short : They are two possible goals. You should:




      • recalculate the total average from the total actual divided by total target if you want to know the average achievement of the total target


      • average on percentage of achievements if you want to know the average achievement of the different tasks, giving each task the same importance.







      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        Intuitively, this is because your target have different values, they have different "weights/importance" into your total target.



        Imagine an extreme case, where you add another very high target : 1,000,000 for instance, and suppose you actually reach 0 on this target. The percentage of achievement for this task is 0, and overall you should be very close to 0% of total achievement. The other targets almost don't count compared to the new main one.



        But if you compute the average directly on the percentage of achievement, then you suppose that the new task counts as much as the old one, only reducing the total achievement percentage by 1/7th.



        In short : They are two possible goals. You should:




        • recalculate the total average from the total actual divided by total target if you want to know the average achievement of the total target


        • average on percentage of achievements if you want to know the average achievement of the different tasks, giving each task the same importance.







        share|cite|improve this answer









        $endgroup$



        Intuitively, this is because your target have different values, they have different "weights/importance" into your total target.



        Imagine an extreme case, where you add another very high target : 1,000,000 for instance, and suppose you actually reach 0 on this target. The percentage of achievement for this task is 0, and overall you should be very close to 0% of total achievement. The other targets almost don't count compared to the new main one.



        But if you compute the average directly on the percentage of achievement, then you suppose that the new task counts as much as the old one, only reducing the total achievement percentage by 1/7th.



        In short : They are two possible goals. You should:




        • recalculate the total average from the total actual divided by total target if you want to know the average achievement of the total target


        • average on percentage of achievements if you want to know the average achievement of the different tasks, giving each task the same importance.








        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 25 at 9:56









        Thomas LesgourguesThomas Lesgourgues

        1,145219




        1,145219






























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