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 = 120, v2 = 115.7.
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: - 63.
- Choose a random positive number for the end value: 56.
Formula and calculation:
(v1 - v2) / v1 =
(- 63 - 56) / - 63 =
-119 / - 63 ≈
1.888888888889 ≈
1.89
Although the absolute difference is negative: -119, the relative decrease change is positive: 1.89. 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:
(120 - 115.7)/|120| =
4.3/120 =
4.3 ÷ 120 =
4.3 ÷ 120 × 100/100 =
(4.3 × 100 ÷ 120)/100 =
(430 ÷ 120)/100 ≈
3.583333333333/100 =
3.583333333333% ≈
3.58%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 120 to the final, end value 115.7:
Rounded off to max. 12 decimal places ≈ 3.583333333333%
Rounded off to max. 2 decimal places ≈ 3.58%
The absolute (actual) difference
120 - 115.7 = 4.3
By what percentage has 120 decreased?
Answer: By ≈ 3.58%
By what percentage is 115.7 smaller than 120?
Answer: By ≈ 3.58%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).