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 = 3, v2 = - 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: - 5.
- Choose a random positive number for the end value: 34.
Formula and calculation:
(v1 - v2) / v1 =
(- 5 - 34) / - 5 =
-39 / - 5 =
7.8
Although the absolute difference is negative: -39, the relative decrease change is positive: 7.8. 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:
(3 - (- 6))/|3| =
(3 + 6)/|3| =
9/3 =
9 ÷ 3 =
9 ÷ 3 × 100/100 =
(9 × 100 ÷ 3)/100 =
(900 ÷ 3)/100 =
300/100 =
300%
The relative percent decrease change
from the original, initial value 3 to the final, end value - 6:
= 300%
The absolute (actual) difference
3 + 6 = 9
By what percentage has 3 decreased?
Answer: By 300%
By what percentage is - 6 smaller than 3?
Answer: By 300%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).