percentage difference between positive and negative numbers

[wyndland]

Hello,
Please refer to the table below

I have been trying to create a formula to show the percentage increase between the 'without' row and the 'with' row.
I've tried ((without - with)/with) and also included the ABS command to try and solve the negative number issue but the results are less than accurate (see bottom row)

Any help would be most gratefully received

Regards
Glen

[TABLE="width: 241"]
<colgroup><col><col><col><col></colgroup><tbody>[TR]
[TD] [/TD]
[TD]Read[/TD]
[TD]Write[/TD]
[TD]Rithmatic[/TD]
[/TR]
[TR]
[TD]Total[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]with[/TD]
[TD]-0.53[/TD]
[TD]0.90[/TD]
[TD]0.16[/TD]
[/TR]
[TR]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[/TR]
[TR]
[TD]without[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD] [/TD]
[TD]-1.58[/TD]
[TD]-0.08[/TD]
[TD]-0.72[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD="align: right"]26.27%[/TD]
[TD="align: right"]66.54%[/TD]
[TD="align: right"]-54.58%[/TD]
[/TR]
</tbody>[/TABLE]

 

[Joe4]

Welcome to the Board!

So, which is your starting value (with or without)?
What exactly is the "negative number" issue?
What does a negative represent, and how should it be handled?
What are your expected results?

 

[wyndland]

Welcome to the Board!

So, which is your starting value (with or without)?
What exactly is the "negative number" issue?
What does a negative represent, and how should it be handled?
What are your expected results?

I'm calculating the reading writing and maths scores for schools who receive music tuition and those that don't
I averaged the totals of 85 schools using the AVERAGE function (some schools were positive and some negative values) for all 3 types (reading, writing, maths). My aim is to show how better the scores are when music is involved. In all 3 instances the scores are better, BUT, some scores feature negative numbers (as in my table). I might have expected an increase of around 200% (if my maths is right!) in the reading total: from -1.58 (without) to .53 (with)

Thanks for getting back so quickly
G

 

[wyndland]

Forgot to add that the starting value is 'without'

thanks Joe4

G

 

[Joe4]

It really depends on what those numbers actually represent.

For example, you wouldn't say that 4 degrees Fahrenheit is twice as warm as 2 degrees Fahrenheit!
Just because the number is twice as big doesn't necessarily mean that the actually heat generated is twice as much.
So we need to understand exactly what these numbers represent and how they are derived for them to have any sort of true meaning.

 

[cerfani]

The value being positive or negative has no affect on the logic to calculate % difference

=(A-B)/A or =(B-A)/A ... % of A difference... you could use either one one would be +, the other - to describe the direction of the difference
=(B-A)/B or =(A-B)/B ... % of B difference

which one you choose is what you are trying to describe

 

[golfboy7]

Hi wyndland,

I hope others on the board will keep me honest.

I believe the formula should be the change between the old number and the new number, divided by the starting number.

For example, if i had 10 apples, and gained 3 more apples, the increase would be the change (+3) divided by the starting number (10) for a % change of 30% increase.

Since you have negative numbers it 'seems' more confusing than it really is. Here's what I came up with:

[TABLE="class: grid, width: 500"]
<tbody>[TR]
[TD][/TD]
[TD]A[/TD]
[TD]B[/TD]
[TD]C[/TD]
[TD]D[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD][/TD]
[TD]Read[/TD]
[TD]Write[/TD]
[TD]Arithmatic[/TD]
[/TR]
[TR]
[TD]2[/TD]
[TD]w/out music[/TD]
[TD]-1.58[/TD]
[TD]-.08[/TD]
[TD]-.72[/TD]
[/TR]
[TR]
[TD]3[/TD]
[TD]w music[/TD]
[TD]-.53[/TD]
[TD].9[/TD]
[TD].16[/TD]
[/TR]
[TR]
[TD]4[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]5[/TD]
[TD]% change[/TD]
[TD]66%[/TD]
[TD]1225%[/TD]
[TD]122%[/TD]
[/TR]
</tbody>[/TABLE]


The formula I wrote for this (assuming it begins in the top left at cell A1):

=ABS((B3-B2)/B2)


That said, sometimes showing a % change is not the best way to communicate the impact. In this case, it may be better to show it as a raw increase, "Reading scores show an increase of 105 basis points when music is included..."

Other veterans please keep me honest.

gb7

Forgot to add that the starting value is 'without'

thanks Joe4

G

 

[cerfani]

Arithmatic would make a great name for a calculator company in the '50s lol

you mean arithmetic

 

[golfboy7]

No no, I mean Eurithmetric! Which would make a great name for a band in the 70s-80s with heavy use of synthesizers.

I'll get that updated. Nice catch!

 

[golfboy7]

Ugh, can't figure out how to edit my post. Sorry, new around here.