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 = 217, v2 = 322.2.
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: 7.
Formula and calculation:
(v1 - v2) / v1 =
(- 91 - 7) / - 91 =
-98 / - 91 =
1.076923076923 ≈
1.08
Although the absolute difference is negative: -98, the relative decrease change is positive: 1.08. 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:
(217 - 322.2)/|217| =
- 105.2/217 =
- 105.2 ÷ 217 =
- 105.2 ÷ 217 × 100/100 =
(- 105.2 × 100 ÷ 217)/100 =
(- 10,520 ÷ 217)/100 =
- 48.479262672811/100 =
- 48.479262672811% ≈
- 48.48%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 217 to the final, end value 322.2:
Not rounded = - 48.479262672811%
Rounded off to max. 2 decimal places ≈ - 48.48%
The absolute (actual) difference
217 - 322.2 = - 105.2
By what percentage has 217 decreased?
Answer: By ≈ - 48.48%
By what percentage is 322.2 smaller than 217?
Answer: By ≈ - 48.48%
The relative percent decrease change is negative,
so in this case we really have a relative percent increase instead
(the value goes up).