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 = 262, v2 = 183.4.
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: - 73.
- Choose a random positive number for the end value: 89.
Formula and calculation:
(v1 - v2) / v1 =
(- 73 - 89) / - 73 =
-162 / - 73 ≈
2.219178082192 ≈
2.22
Although the absolute difference is negative: -162, the relative decrease change is positive: 2.22. 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:
(262 - 183.4)/|262| =
78.6/262 =
78.6 ÷ 262 =
78.6 ÷ 262 × 100/100 =
(78.6 × 100 ÷ 262)/100 =
(7,860 ÷ 262)/100 =
30/100 =
30%
The relative percent decrease change
from the original, initial value 262 to the final, end value 183.4:
= 30%
The absolute (actual) difference
262 - 183.4 = 78.6
By what percentage has 262 decreased?
Answer: By 30%
By what percentage is 183.4 smaller than 262?
Answer: By 30%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).