Percentage increase from a negative number to a positive one

[bazbarrow]

Hi,

I'm trying to work out the percentage increase from a negative number (-21) to a positive number (941) but I'm very confused...can anyone help please?

Thanks
Richard

 

[Joe4]

From a mathematical standpoint, I don't know if it makes any sense to calculate a percentage increase when going from a negative number to a positive number.
Any calculated value may not really have any inherent meaning or significance.

What exactly do these numbers represent?
Where do they come from?

You can see a discussion on this topic here: Any trick to calculating percentages when the base is a negative number

 

[Toadstool]

Hi Bazbarrow,

I think the confusing part is you can end up with a negative percentage when you can see that you have increased between the starting and ending numbers. Using the ABSolute function should address this so you only get negative when you have decreased.

Bazbarrow.xlsx
	G	H	I	J
1	Start	End		Result %
2	-21	941		4580.952
3	1	2		100
4	-5	5		200
5	10	20		100
6	10	2		-80
Sheet1

Cell Formulas
Range	Formula
J2:J6	J2	=((H2-G2)/ABS(G2))*100

 

[Joe4]

Hi Bazbarrow,

I think the confusing part is you can end up with a negative percentage when you can see that you have increased between the starting and ending numbers. Using the ABSolute function should address this so you only get negative when you have decreased.

Bazbarrow.xlsx
	G	H	I	J
1	Start	End		Result %
2	-21	941		4580.952
3	1	2		100
4	-5	5		200
5	10	20		100
6	10	2		-80
Sheet1

Cell Formulas
Range	Formula
J2:J6	J2	=((H2-G2)/ABS(G2))*100

I am really not sure how meaningful those results are though (sure you get numbers, but do they really mean anything?).
Imagine if G2 was 0 (which lies between negative and positive numbers, so is a real possibility). You would get errors with that formula.

 

[bazbarrow]

Hi Bazbarrow,

I think the confusing part is you can end up with a negative percentage when you can see that you have increased between the starting and ending numbers. Using the ABSolute function should address this so you only get negative when you have decreased.

Bazbarrow.xlsx
	G	H	I	J
1	Start	End		Result %
2	-21	941		4580.952
3	1	2		100
4	-5	5		200
5	10	20		100
6	10	2		-80
Sheet1

Cell Formulas
Range	Formula
J2:J6	J2	=((H2-G2)/ABS(G2))*100

Thanks so the answer is a 4,581% increase? But the thing that's confusing me is the percentage increase from 1 to 941 is a 94000% so surely the increase from -21 to 941 would, be a much higher figure that 94000%? Or am I missing something? Thanks Richard

 

[Joe4]

Thanks so the answer is a 4,581% increase? But the thing that's confusing me is the percentage increase from 1 to 941 is a 94000% so surely the increase from -21 to 941 would, be a much higher figure that 94000%? Or am I missing something? Thanks Richard

That is what I am trying to tell you. Many times, if trying to figure out the percent change going from a negative number to a positive number, the values you come up with are rather arbitrary and meaningless. It often doesn't make any sense, from a mathematical concept, trying to figure out a percentage change going from a negative to a positive number (sort of like division by zero).

Can you answer the questions I asked in my first reply?
Maybe if we have some idea of what these numbers actually represent, we can identify other ways of going about it, or accepted industry standards for such things.

 

[bazbarrow]

That is what I am trying to tell you. Many times, if trying to figure out the percent change going from a negative number to a positive number, the values you come up with are rather arbitrary and meaningless. It often doesn't make any sense, from a mathematical concept, trying to figure out a percentage change going from a negative to a positive number (sort of like division by zero).

Can you answer the questions I asked in my first reply?
Maybe if we have some idea of what these numbers actually represent, we can identify other ways of going about it, or accepted industry standards for such things.

Thanks Joe. The numbers are the additional number of facebook followers of a business page. In ione month they had -21 (lost 21 followers) and the following month put on 941 followers. I want to show the increase in a percentage as I can do with other months. Thanks Richard

 

[Joe4]

As I mentioned (as you have seen/demonstrated), trying to show percent change based on those numbers results in meaningless numbers.
I think it would be better to show percent growth, in which you would take the number of additions/losses, compared to the total number.

For example, let's say that going in to last month, you had 2100 followers, and then you lost 21, so you are left with 979.
So, your percent change for that month would be -1.0% (-21/2100).

Now, let's say you the following month you gained 941.
So, your percent change for that month would be 45.3% (941/2079).

If you wanted the total change for the two months, it would be 43.8% (920/2100).

I believe that those are much more useful (and sensical) statistics.

 

[bazbarrow]

As I mentioned (as you have seen/demonstrated), trying to show percent change based on those numbers results in meaningless numbers.
I think it would be better to show percent growth, in which you would take the number of additions/losses, compared to the total number.

For example, let's say that going in to last month, you had 2100 followers, and then you lost 21, so you are left with 979.
So, your percent change for that month would be -1.0% (-21/2100).

Now, let's say you the following month you gained 941.
So, your percent change for that month would be 45.3% (941/2079).

If you wanted the total change for the two months, it would be 43.8% (920/2100).

I believe that those are much more useful (and sensical) statistics.

Thanks Joe, that's really helpful. Just to confuse the issue a little further....the -21 figure was the average number of followers lost/gained over a 3 month period and then over the next 3 month period the average number of followers lost/gained was 941. So would I just take the number of followers at the start of each 3 month period and then apply your logic from above?

 

[Joe4]

It is a bit confusing. Are you trying to get "averages" of "averages"?
If -21 is the "average" over a 3 month period, does that mean the real number lost over that time was -63 (which is -21*3)?
What exactly are your monthly numbers?
And what exactly are you trying to show/accomplish?

You have to be REALLY careful with statistics, as if they are not used in the proper context, they can be very misleading (many people actually take advantage of this fact when making distored arguments).

For example, let's say that we have two companies, Company A and Company B.
Let's say that Company A had a profit of $1 in year 1, and then a profit of $2 in year 2.
And let's say that Company B had a profit of $400 in year 1, and then a profit of $500 in year 2.

Who would you say had the better year 2? I think most people would agree it is Company B.
However, if you looked at profit growth from year 1 to year 2, Company A had 100% profit growth, while Company B had 25% profit growth.
So if you only looked at that percentage, you would be inclined to say Company A had the better year 2.

Just like "words", "numbers" taken out of context can be very misleading and not really informative.