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 = 125, v2 = 127.4.
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: - 48.
- Choose a random positive number for the end value: 38.
Formula and calculation:
(v1 - v2) / v1 =
(- 48 - 38) / - 48 =
-86 / - 48 ≈
1.791666666667 ≈
1.79
Although the absolute difference is negative: -86, the relative decrease change is positive: 1.79. 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:
(125 - 127.4)/|125| =
- 2.4/125 =
- 2.4 ÷ 125 =
- 2.4 ÷ 125 × 100/100 =
(- 2.4 × 100 ÷ 125)/100 =
(- 240 ÷ 125)/100 =
- 1.92/100 =
- 1.92%
The relative percent decrease change
from the original, initial value 125 to the final, end value 127.4:
= - 1.92%
The absolute (actual) difference
125 - 127.4 = - 2.4
By what percentage has 125 decreased?
Answer: By - 1.92%
By what percentage is 127.4 smaller than 125?
Answer: By - 1.92%
The relative percent decrease change is negative,
so in this case we really have a relative percent increase instead
(the value goes up).