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 = 24, v2 = - 42.6.
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: - 26.
- Choose a random positive number for the end value: 8.
Formula and calculation:
(v1 - v2) / v1 =
(- 26 - 8) / - 26 =
-34 / - 26 ≈
1.307692307692 ≈
1.31
Although the absolute difference is negative: -34, the relative decrease change is positive: 1.31. 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:
(24 - (- 42.6))/|24| =
(24 + 42.6)/|24| =
66.6/24 =
66.6 ÷ 24 =
66.6 ÷ 24 × 100/100 =
(66.6 × 100 ÷ 24)/100 =
(6,660 ÷ 24)/100 =
277.5/100 =
277.5%
The relative percent decrease change
from the original, initial value 24 to the final, end value - 42.6:
= 277.5%
The absolute (actual) difference
24 + 42.6 = 66.6
By what percentage has 24 decreased?
Answer: By 277.5%
By what percentage is - 42.6 smaller than 24?
Answer: By 277.5%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).