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 = 49.5, v2 = 50.8.
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: - 56.
- Choose a random positive number for the end value: 54.
Formula and calculation:
(v1 - v2) / v1 =
(- 56 - 54) / - 56 =
-110 / - 56 ≈
1.964285714286 ≈
1.96
Although the absolute difference is negative: -110, the relative decrease change is positive: 1.96. 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:
(49.5 - 50.8)/|49.5| =
- 1.3/49.5 =
- 1.3 ÷ 49.5 =
- 1.3 ÷ 49.5 × 100/100 =
(- 1.3 × 100 ÷ 49.5)/100 =
(- 130 ÷ 49.5)/100 ≈
- 2.626262626263/100 =
- 2.626262626263% ≈
- 2.63%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 49.5 to the final, end value 50.8:
Rounded off to max. 12 decimal places ≈ - 2.626262626263%
Rounded off to max. 2 decimal places ≈ - 2.63%
The absolute (actual) difference
49.5 - 50.8 = - 1.3
By what percentage has 49.5 decreased?
Answer: By ≈ - 2.63%
By what percentage is 50.8 smaller than 49.5?
Answer: By ≈ - 2.63%
The relative percent decrease change is negative,
so in this case we really have a relative percent increase instead
(the value goes up).