Focal Point
Definition of "Basis Value"

This topic can be found at:
http://forums.informationbuilders.com/eve/forums/a/tpc/f/1461084022/m/2717074595

December 16, 2010, 04:59 PM
JBK
Definition of "Basis Value"
What is "Basis Value", and what page in the documentation is it covered? 3 of us have looked and couldn't find it.

Thank you.


WebFOCUS 7.6.11, Linux, HTML, PDF, AHTML, EXCEL
December 17, 2010, 08:43 AM
Bob Jude Ferrante
Basis is the standard on which 100% is based. It prevents divide-by-zero in situations where you might have a target of 0, because in descending measures your target is the denominator in the calculation.

If you set a basis of 10 on a descending measure, and the target is 0, and your actual is 10, then you are at 0% achieved. If the basis were 20, you'd be at 50% achieved.

Not sure why this isn't in the doc but we'll correct that.

Also please see http://forums.informationbuild...=363101451#363101451

and

http://forums.informationbuild...=369104021#369104021

There is a search function on the Forum. That's how I found these.

thanks


Bob Jude Ferrante
Director of Business and Development
WebFOCUS Performance Management
Bob_Ferrante@ibi.com
917-339-5105

I'll take any questions about PMF - business or technical - anytime!

December 20, 2010, 05:55 PM
JBK
Thanks Bob.

We still were a little unsure, so for clarification, are either of these interpretetations correct?

1. In the situation where a descending measure's target is zero, the basis value is used instead of the target value to avoid division by zero. In this case is the formula to calculate Percent of Target Reached (% Achieved): (Basis - Actual) / Basis? This would would work for the first 2 examples below.

  
Basis    Actual    Target    % Achieved
-----    ------    ------    ----------
   10        10         0            0%
   10        20         0           50%
   20        10         0          -50%



How would this work if the basis were 20 and the actual were 10? Using (Basis - Actual) / Basis, (10 - 20) / 20 = -0.5, which is -50%.

2. The other interpretation we came up with was:
(Actual - Basis) / (Basis - Target)
which would be used regardless of whether the target is 0 or not for a descending measure.

We also need to be able to explain all this to our end users who supply the info we use to create the measures.

Thank you.


WebFOCUS 7.6.11, Linux, HTML, PDF, AHTML, EXCEL
January 04, 2011, 09:44 AM
EricH
As Bob said, Basis is used for descending Measures when the Target is 0 to avoid divide by 0 situations.

The formula for % Reached is ((BASIS- ACTUAL) / (BASIS - TARGET)) * 100.0. So expanding on your data:

 
Basis    Actual    Target      % Reached
-----    ------    ------     ----------
   10        20         0          -100%
   10        15         0           -50%
   10        10         0             0%
   10         5         0            50%
   10         0         0           100%
 



You can also use Basis when your Target is very small to avoid excessively large values of % Reached.

EricH
January 04, 2011, 11:38 AM
JBK
Thank you, Eric.


WebFOCUS 7.6.11, Linux, HTML, PDF, AHTML, EXCEL
April 05, 2012, 09:42 AM
<cae>
This is the first time using Focal Point so I hope I am doing this properly.
I have been trying to figure out the best way to calculate % target reached for descending measures. I understand that using Basis value avoids the Dividing by 0 issue but what if the target equals the Basis value? Aren't we back to the dividing by 0 issue. Also, I have found that if your target and actual numbers are greater than the basis value the Basis value calculation gives incorrect results. If there were a way to ensure that there were never targets of 0, wouldn't it always be best to use the Target Value calculation for % target reached for descending measures?
Any thoughts?
April 05, 2012, 06:10 PM
Bob Jude Ferrante
For some reason I cannot fathom, a complete description of Basis isn't in the doc...

PMF calculates Percent Reached for descending Meausres by dividing the Target into
the Actual value and multiplying the result by 100. If the descending Measure had a
Target of 0, this would have resulted in a Divide by Zero, which would have been
mathematically invalid. Special handling is therefore required for Measure Targets that
are set to zero.

In cases where you had a target of 1 or a fractional target, and an Actual that was many
multiples higher (e.g., a Target of .05 and an Actual of 25), you would see a seemingly
abnormally high Percent Reached (sometimes so high as to overflow and display *******
as the Percent Reached).

Basis controls where you would have zero Percent Reached. The basis is the point you
would exceed with your Descending Measure greater than which your Percent Reached
would start moving into the negative. Any Actuals that were greater would show a
negative Percent Reached; any that were less will show a positive Percent Reached.
Setting the Basis gives you control over how Percent Reached is calculated so you can
see more reasonable-looking Percents Reached.

How Descending Measure Basis Handling Works

The special handling lets you pick a defined numeric value as your zero crossing for
Percent Reached. The value can be sufficiently large that you would never exceed it, or
you can adjust it as needed until your numbers look reasonable.

If you set a Basis for a Descending Measure, the calculation for Percent Reached
subtracts the Actual from the Basis amount and the Target for the Basis amount, which
rebalances the Percent Reached to give you more control when Target numbers get very
small.

-----
What this means: If the target for your descending measure SUMS out to equal the basis exactly (and note that if your measure uses continuous rather than discrete values the odds of this are QUITE LOW), you would in concept hit a divide by zero but you never do, since we defend against divide by zero deterministically by setting set Pct Reached to 0 rather than having "undetermined value" for an answer (and/or having WebFOCUS throw an error halting processing).

Hope this helps.


Bob Jude Ferrante
Director of Business and Development
WebFOCUS Performance Management
Bob_Ferrante@ibi.com
917-339-5105

I'll take any questions about PMF - business or technical - anytime!

April 11, 2012, 04:52 PM
<cae>
Thank you Bob.

I have now moved on to our "Range" measures. I was trying to figure out the formula for %target reached. I thought I had it:
(Target-ABS(Actual-Target))/Target. This works most of the time but still not for everything. Do you know the formula?
Thanks,
April 11, 2012, 05:50 PM
Bob Jude Ferrante
Here's a tip: Have a look in A_COMPUTE_RPT_VARS.FEX and its children. All the answers to your questions are there. :-)


Bob Jude Ferrante
Director of Business and Development
WebFOCUS Performance Management
Bob_Ferrante@ibi.com
917-339-5105

I'll take any questions about PMF - business or technical - anytime!

April 13, 2012, 12:22 PM
<cae>
Hi Bob,
I guess I need to clarify that I am a Business Analyst, not a developer. I do not have the capability to look at system files or code. If there is a manual I could look there. Otherwise I need to try to get help from other people.
Thanks
April 13, 2012, 12:31 PM
Bob Jude Ferrante
I'd love to... but am in the middle of getting PMF 5.3.1 ready to ship. Anyone else want to help her right away?

Otherwise, I'll get back to you next week.


Bob Jude Ferrante
Director of Business and Development
WebFOCUS Performance Management
Bob_Ferrante@ibi.com
917-339-5105

I'll take any questions about PMF - business or technical - anytime!

April 17, 2012, 05:35 AM
AdamMcGrath
I am working on Linux.It has some problem over documents configurations.It is terminated by entering a function command.



Event management
April 17, 2012, 10:54 AM
Bob Jude Ferrante
Basically gross percent reached is:
100.0 - ABS(SUM OF(Target_Value) - SUM OF(Actual_Value))/SUM OF(Target_Value) 


In the case of percents and rations you have to take the division into numerators and denominators into account

100.0 - ABS(SUM OF(Target_Numerator_Value)/SUM OF(Target_Denominator_Value)) - (SUM OF(Actual_Numerator_Value)/SUM OF(Actual_Denominator_Value))/(SUM OF(Target_Numerator_Value)/SUM OF(Target_Denominator_Value)) 


If Target ever SUMs to a zero amount we set it to 0.

This doesn't show all the breakpoints we calculate to draw the colours (we do those based on applying thresholds you set), but all use the same pattern.

Hope this helps. Note that it's pretty tedious to type this stuff into this primitive online editor so I hope I didn't make any typing errors. But this should give you an idea.


Bob Jude Ferrante
Director of Business and Development
WebFOCUS Performance Management
Bob_Ferrante@ibi.com
917-339-5105

I'll take any questions about PMF - business or technical - anytime!

April 17, 2012, 03:42 PM
<cae>
Bob,
Thank-you, I think.
This will be tough to test for percents and ratios. A little challenge to keep me busy.