The relative decrease change. Definition:
The relative decrease change is the difference in an indicator over two periods in time, v1 - v2, relative to the value of the indicator in the earlier period, v1.
- Where:
- v1 - is called the reference value (original, initial number);
- v2 - is called the new value (the end value).
- In our case: v1 = 90, v2 = 67.
The relative decrease change. Formula:
The relative decrease change =
The actual change / |v1|
(v1 - v2) / |v1| =
- Legend:
- v1 - the original number
- |v1| - the positive value of v1, |v1| >= 0. By example: |10| = 10; |-10| = 10.
- v2 - the new value
- The actual change = v1 - v2
- / - the fraction bar (division)
Why do we use |v1| in the formula instead of v1?
- Let's see what happens if we use v1 instead of |v1|:
- Choose a random negative number as the initial value: - 31.
- Choose a random positive number for the end value: 52.
Formula and calculation:
(v1 - v2) / v1 =
(- 31 - 52) / - 31 =
-83 / - 31 ≈
2.677419354839 ≈
2.68
Although the absolute difference is negative: -83, the relative decrease change is positive: 2.68. By using |v1| instead of v1, the error is corrected.
The relative percent decrease change. Detailed calculations below
By multiplying a number by the fraction 100/100,
we change only the form of the result, not the result.
- 100/100 = 100% = 100 ÷ 100 = 1.
- n × 100/100 = (n × 100)/100 = (n × 100)%, any number.
The relative percent decrease change. Formula:
The relative percent decrease change =
The relative decrease change × 100/100 =
(The relative decrease change × 100)/100 =
(The relative decrease change × 100)%
Calculate the relative percent decrease change:
(90 - 67)/|90| =
23/90 =
23 ÷ 90 =
23 ÷ 90 × 100/100 =
(23 × 100 ÷ 90)/100 =
(2,300 ÷ 90)/100 ≈
25.555555555556/100 =
25.555555555556% ≈
25.56%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 90 to the final, end value 67:
Rounded off to max. 12 decimal places ≈ 25.555555555556%
Rounded off to max. 2 decimal places ≈ 25.56%
The absolute (actual) difference
90 - 67 = 23
By what percentage has 90 decreased?
Answer: By ≈ 25.56%
By what percentage is 67 smaller than 90?
Answer: By ≈ 25.56%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).