Problem with Averages

G

garfas

New Member
Joined
Oct 22, 2018
Messages
2
Hi All,

I'm working on this problem about test scores and I'm trying to figure out why I'm getting a different number when I get a mean of pupil grade score percentages versus when I do the other way by getting a mean for each individual test and then averaging that? I have noticed that if the the number of questions in each test are equal, I don't have this problem (see example 2) Any help greatly appreciated? Gar



EXAMPLE1




Out ofTOTAL
Test
Test
EXAMPLE2




Out ofTOTAL
Test
Test

<colgroup><col style="width:48pt" width="64" span="2"> <col style="mso-width-source:userset;mso-width-alt:3145;width:65pt" width="86"> <col style="mso-width-source:userset;mso-width-alt:3474;width:71pt" width="95"> <col style="mso-width-source:userset;mso-width-alt:2925;width:60pt" width="80"> <col style="width:48pt" width="64" span="2"> <col style="mso-width-source:userset;mso-width-alt:4461;width:92pt" width="122"> <col style="mso-width-source:userset;mso-width-alt:1170;width:24pt" width="32"> <col style="width:48pt" width="64" span="3"> </colgroup><tbody>
[TD="width: 64"][/TD]
[TD="width: 64"][/TD]
[TD="class: xl63, width: 86"]Test1
[/TD]
[TD="class: xl63, width: 95"]Test2
[/TD]
[TD="class: xl63, width: 80"]Test3
[/TD]
[TD="width: 64"][/TD]
[TD="width: 64"][/TD]
[TD="width: 122"][/TD]
[TD="width: 32"][/TD]
[TD="width: 64"][/TD]
[TD="width: 64"][/TD]
[TD="width: 64"][/TD]

[TD="class: xl64"] 12
[/TD]
[TD="class: xl64"]20[/TD]
[TD="class: xl64"]10[/TD]

[TD="class: xl64"]Out of
[/TD]
[TD="class: xl64"] Pupil Avg %
[/TD]

[TD="class: xl66"]Pupil1
[/TD]
[TD="class: xl67"]12[/TD]
[TD="class: xl68"]10[/TD]
[TD="class: xl68"]9[/TD]
[TD="class: xl68"]31[/TD]
[TD="class: xl69"]42[/TD]
[TD="class: xl65, align: right"]73.809523810%[/TD]

[TD="class: xl66"]Pupil2
[/TD]
[TD="class: xl70"]8[/TD]
[TD="class: xl64"]12[/TD]
[TD="class: xl64"]7[/TD]
[TD="class: xl64"]27[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]64.285714286%[/TD]

[TD="class: xl66"]Pupil3
[/TD]
[TD="class: xl70"]12[/TD]
[TD="class: xl64"]14[/TD]
[TD="class: xl64"]8[/TD]
[TD="class: xl64"]34[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]80.952380952%[/TD]

[TD="class: xl66"]Pupil4
[/TD]
[TD="class: xl70"]12[/TD]
[TD="class: xl64"]14[/TD]
[TD="class: xl64"]9[/TD]
[TD="class: xl64"]35[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]83.333333333%[/TD]

[TD="class: xl66"]Pupil5
[/TD]
[TD="class: xl70"]8[/TD]
[TD="class: xl64"]8[/TD]
[TD="class: xl64"]8[/TD]
[TD="class: xl64"]24[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]57.142857143%[/TD]

[TD="class: xl66"]Pupil6
[/TD]
[TD="class: xl72"]12[/TD]
[TD="class: xl73"]13[/TD]
[TD="class: xl73"]9[/TD]
[TD="class: xl73"]34[/TD]
[TD="class: xl74"]42[/TD]
[TD="class: xl65, align: right"]80.952380952%[/TD]

[TD="class: xl66"]Avg[/TD]
[TD="align: right"]10.66666667[/TD]
[TD="align: right"]11.83333333[/TD]
[TD="class: xl75, align: right"]8.3333333[/TD]
[TD="class: xl64"]30.83333[/TD]

[TD="class: xl78, align: right"] 73.4126984%
[/TD]

[TD="class: xl66, colspan: 2"]Mean Pupil Avg %[/TD]

[TD="class: xl66"]Avg %[/TD]
[TD="align: right"]0.888888889[/TD]
[TD="align: right"]0.591666667[/TD]
[TD="align: right"]0.83333333[/TD]

[TD="class: xl79"]Mean
[/TD]
[TD="class: xl66, colspan: 2"]Test Avg %
[/TD]
[TD="class: xl78, align: right"] 77.1296296%
[/TD]

[TD="class: xl76, colspan: 3"] Why are these Averages different?
[/TD]

[TD="class: xl63"]Test1
[/TD]
[TD="class: xl63"]Test2
[/TD]
[TD="class: xl63"]Test3
[/TD]

[TD="class: xl64"][/TD]

[TD="class: xl64"] 14
[/TD]
[TD="class: xl64"] 14
[/TD]
[TD="class: xl64"] 14
[/TD]

[TD="class: xl64"]Out of[/TD]
[TD="class: xl64"] Pupil Avg %
[/TD]

[TD="class: xl66"]Pupil1
[/TD]
[TD="class: xl67"]12[/TD]
[TD="class: xl68"]10[/TD]
[TD="class: xl68"]9[/TD]
[TD="class: xl68"]31[/TD]
[TD="class: xl69"]42[/TD]
[TD="class: xl65, align: right"]73.809523810%[/TD]

[TD="class: xl66"]Pupil2
[/TD]
[TD="class: xl70"]8[/TD]
[TD="class: xl64"]12[/TD]
[TD="class: xl64"]7[/TD]
[TD="class: xl64"]27[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]64.285714286%[/TD]

[TD="class: xl66"]Pupil3
[/TD]
[TD="class: xl70"]12[/TD]
[TD="class: xl64"]14[/TD]
[TD="class: xl64"]8[/TD]
[TD="class: xl64"]34[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]80.952380952%[/TD]

[TD="class: xl66"]Pupil4
[/TD]
[TD="class: xl70"]12[/TD]
[TD="class: xl64"]14[/TD]
[TD="class: xl64"]9[/TD]
[TD="class: xl64"]35[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]83.333333333%[/TD]

[TD="class: xl66"]Pupil5
[/TD]
[TD="class: xl70"]8[/TD]
[TD="class: xl64"]8[/TD]
[TD="class: xl64"]8[/TD]
[TD="class: xl64"]24[/TD]
[TD="class: xl71"]42[/TD]
[TD="class: xl65, align: right"]57.142857143%[/TD]

[TD="class: xl66"]Pupil6
[/TD]
[TD="class: xl72"]12[/TD]
[TD="class: xl73"]13[/TD]
[TD="class: xl73"]9[/TD]
[TD="class: xl73"]34[/TD]
[TD="class: xl74"]42[/TD]
[TD="class: xl65, align: right"]80.952380952%[/TD]

[TD="class: xl66"]Avg[/TD]
[TD="align: right"]10.66666667[/TD]
[TD="align: right"]11.83333333[/TD]
[TD="class: xl75, align: right"]8.3333333[/TD]
[TD="class: xl64"]30.83333[/TD]

[TD="class: xl77, align: right"] 73.4126984%
[/TD]

[TD="class: xl66, colspan: 2"]Mean Pupil Avg %[/TD]

[TD="class: xl66"]Avg %[/TD]
[TD="align: right"]0.761904762[/TD]
[TD="align: right"]0.845238095[/TD]
[TD="align: right"]0.5952381[/TD]

[TD="class: xl79"]Mean[/TD]
[TD="class: xl66, colspan: 2"]Test Avg %
[/TD]
[TD="class: xl77, align: right"] 73.4126984%
[/TD]

[TD="class: xl76, colspan: 3"] Ok when test question numbers equal
[/TD]

</tbody>
 

Excel Facts

How to calculate loan payments in Excel?
Use the PMT function: =PMT(5%/12,60,-25000) is for a $25,000 loan, 5% annual interest, 60 month loan.
Sort by date Sort by votes
Hi there.

If youre worried that excel is getting it wrong, dont be. The calculations come out differently because of what it is that you are averaging. Averaging averages can and does reult in this kind of apparent anomaly.
 
Last edited:
Upvote 0
Ok. I've been doing some research on this. Now I'm wondering, as the test question number is different, if I should be using weighted averages using SUMPRODUCT
 
Upvote 0
You must log in or register to reply here.

Similar threads

JenniferMurphy
  • Question Question
Can someone help me understand Bayesian averages?
Replies
1
Views
132
FormulasOnly
F
H
  • Question Question
Calculating avg. prices across specific hours of the year from a dataset using PivotTables?
Replies
0
Views
550
helnuma2k
H
C
  • Solved
Averaging + & - times in Text format
2
Replies
10
Views
586
Alex Blakenburg
A
tperk100
  • Solved
AVG Function not Updating Range
2
Replies
11
Views
797
Automatrix
A
P
  • Solved
Average sales for the previous 3 months for each product
Replies
2
Views
341
paun_shotts
P

Forum statistics

Threads
1,223,893
Messages
6,175,240
Members
452,621
Latest member
Laura_PinksBTHFT

Share this page

We've detected that you are using an adblocker.

We have a great community of people providing Excel help here, but the hosting costs are enormous. You can help keep this site running by allowing ads on MrExcel.com.
Allow Ads at MrExcel

Which adblocker are you using?

Disable AdBlock

Follow these easy steps to disable AdBlock

1)Click on the icon in the browser’s toolbar.
2)Click on the icon in the browser’s toolbar.
2)Click on the "Pause on this site" option.
Go back

Disable AdBlock Plus

Follow these easy steps to disable AdBlock Plus

1)Click on the icon in the browser’s toolbar.
2)Click on the toggle to disable it for "mrexcel.com".
Go back

Disable uBlock Origin

Follow these easy steps to disable uBlock Origin

1)Click on the icon in the browser’s toolbar.
2)Click on the "Power" button.
3)Click on the "Refresh" button.
Go back

Disable uBlock

Follow these easy steps to disable uBlock

1)Click on the icon in the browser’s toolbar.
2)Click on the "Power" button.
3)Click on the "Refresh" button.
Go back
Back
Top