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 = 131, v2 = 115.1.
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: - 91.
- Choose a random positive number for the end value: 54.
Formula and calculation:
(v1 - v2) / v1 =
(- 91 - 54) / - 91 =
-145 / - 91 ≈
1.593406593407 ≈
1.59
Although the absolute difference is negative: -145, the relative decrease change is positive: 1.59. 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:
(131 - 115.1)/|131| =
15.9/131 =
15.9 ÷ 131 =
15.9 ÷ 131 × 100/100 =
(15.9 × 100 ÷ 131)/100 =
(1,590 ÷ 131)/100 ≈
12.137404580153/100 =
12.137404580153% ≈
12.14%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 131 to the final, end value 115.1:
Rounded off to max. 12 decimal places ≈ 12.137404580153%
Rounded off to max. 2 decimal places ≈ 12.14%
The absolute (actual) difference
131 - 115.1 = 15.9
By what percentage has 131 decreased?
Answer: By ≈ 12.14%
By what percentage is 115.1 smaller than 131?
Answer: By ≈ 12.14%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).