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 = 126, v2 = 122.8.
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: - 15.
- Choose a random positive number for the end value: 55.
Formula and calculation:
(v1 - v2) / v1 =
(- 15 - 55) / - 15 =
-70 / - 15 ≈
4.666666666667 ≈
4.67
Although the absolute difference is negative: -70, the relative decrease change is positive: 4.67. 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:
(126 - 122.8)/|126| =
3.2/126 =
3.2 ÷ 126 =
3.2 ÷ 126 × 100/100 =
(3.2 × 100 ÷ 126)/100 =
(320 ÷ 126)/100 ≈
2.539682539683/100 =
2.539682539683% ≈
2.54%
(Rounded off to max. 2 decimal places)
The relative percent decrease change
from the original, initial value 126 to the final, end value 122.8:
Rounded off to max. 12 decimal places ≈ 2.539682539683%
Rounded off to max. 2 decimal places ≈ 2.54%
The absolute (actual) difference
126 - 122.8 = 3.2
By what percentage has 126 decreased?
Answer: By ≈ 2.54%
By what percentage is 122.8 smaller than 126?
Answer: By ≈ 2.54%
The relative percent decrease change is positive,
so we really have a relative percent decrease
(the value goes down).