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 = - 10,000, v2 = 98.8.
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: - 22.
- Choose a random positive number for the end value: 39.
Formula and calculation:
(v1 - v2) / v1 =
(- 22 - 39) / - 22 =
-61 / - 22 ≈
2.772727272727 ≈
2.77
Although the absolute difference is negative: -61, the relative decrease (change) is positive: 2.77. 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):
(- 10,000 - 98.8)/|- 10,000| =
- 10,098.8/10,000 =
- 10,098.8 ÷ 10,000 =
- 10,098.8 ÷ 10,000 × 100/100 =
(- 10,098.8 × 100 ÷ 10,000)/100 =
(- 1,009,880 ÷ 10,000)/100 =
- 100.988/100 =
- 100.988% ≈
- 100.99%
(Rounded off to max. 2 decimal places)
The relative percent decrease (change)
from the original, initial value - 10,000 to the final, end value 98.8:
Not rounded = - 100.988%
Rounded off to max. 2 decimal places ≈ - 100.99%
The absolute (actual) difference
- 10,000 - (98.8) = - 10,000 - 98.8 = - 10,098.8
The relative percent decrease (change) is negative,
so in this case we really have a relative percent increase instead
(the value goes up).