How to show % increase when accuracy decreases?

[tibado]

Ok, I'm stuck on this one and hope you can help

Here is the sample data

Date 1 2 3

Made 1167 1318 1225

Passed 1121 1203 1209

Passed - As a % of Made 96% 91% 99%

% Increase in Accuracy 0% X% Y%

1. The ‘Date’ will continue for an indeterminate amount of time.
2. The ‘Made’ are the total produced for each ‘Date’ and may increase or
decrease from the prior ‘Date’.
3. The ‘Passed’ are derived from how many of the ‘Made’ did not fail.
4. The ‘Passed – As a % of Made is equal to ‘Passed’ divided by ‘Made’ as
shown as a % and could never exceed 100%.
a. Example: For Date 1 1121 / 1167 * .01 = 96%
5. The ‘% Increase in Accuracy is the problem, I need to derive for ‘Date 2’
the percentage of increase of ‘Passed’ parts as it is related to ‘Date 1’
and show it as an increase or decrease trend towards 100% accuracy.
6. Then I need to derive for ‘Date 3’ the percentage of increase of ‘Passed’
parts as it relates to ‘Date 2’ and so on…

So I need to solve for X% and Y% as a trend towards the goal of 100% passed.

Thanks in Advance.

 

[Eduardo]

Hi,
Two ways
1
Difference in the %

Date2-Date1

or as a Calculation

(Passed date2 / Passed date1) - 1

 

[Luke M]

Note: In example 4a, you should not be multiplying by .01 as that would give
you less than 1% as an answer.

I think you've overthinking the problem. The change is -5% and 8%
respectively. Just subtract the two values.

Note that even though you passed more parts, the raiot of pass/made
decreased, thus your percentage is negative (process is getting worse, not
better)