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 = 7, v2 = 15.
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: - 53.
- Choose a random positive number for the end value: 75.
Formula and calculation:
(v1 - v2) / v1 =
(- 53 - 75) / - 53 =
-128 / - 53 ≈
2.415094339623 ≈
2.42
Although the absolute difference is negative: -128, the relative decrease change is positive: 2.42. 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:
(7 - 15)/|7| =
- 8/7 =
- 8 ÷ 7 =
- 8 ÷ 7 × 100/100 =
(- 8 × 100 ÷ 7)/100 =
(- 800 ÷ 7)/100 ≈
- 114.285714285714/100 =
- 114.285714285714% ≈
- 114.29%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 7 to the final, end value 15:
Rounded off to max. 12 decimal places ≈ - 114.285714285714%
Rounded off to max. 2 decimal places ≈ - 114.29%
The absolute (actual) difference
7 - 15 = - 8
By what percentage has 7 decreased?
Answer: By ≈ - 114.29%
By what percentage is 15 smaller than 7?
Answer: By ≈ - 114.29%
The relative percent decrease change is negative,
so in this case we really have a relative percent increase instead
(the value goes up).