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.
- Namely:
- v1 - is called the reference value (original, initial number);
- v2 - is called the new value (the end value).
- In our case: v1 = 1,480, v2 = 1,226.7.
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: - 21.
- Choose a random positive number for the end value: 69.
Formula and calculation:
(v1 - v2) / v1 =
(- 21 - 69) / - 21 =
-90 / - 21 ≈
4.285714285714 ≈
4.29
Although the absolute difference is negative: -90, the relative decrease (change) is positive: 4.29. 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):
(1,480 - 1,226.7)/|1,480| =
253.3/1,480 =
253.3 ÷ 1,480 =
253.3 ÷ 1,480 × 100/100 =
(253.3 × 100 ÷ 1,480)/100 =
(25,330 ÷ 1,480)/100 ≈
17.114864864865/100 =
17.114864864865% ≈
17.11%
(Rounded off to max. 2 decimal places)
The relative percent decrease (change)
from the original, initial value 1,480 to the final, end value 1,226.7:
Rounded off to max. 12 decimal places ≈ 17.114864864865%
Rounded off to max. 2 decimal places ≈ 17.11%
The absolute (actual) difference
1,480 - 1,226.7 = 253.3
The relative percent decrease (change) is positive,
so we really have a relative percent decrease
(the value goes down).