# How to get the Uncertainty of a percentage change

• usehn
In summary, there is a measurement with uncertainties for two years, with Year 1 Rain at 100mm (80-120mm) and Year 2 Rain at 120mm (103-131mm). The percentage change in rain for Year 2 compared to Year 1 is 20%, and the question is whether there is a way to determine the uncertainty associated with this percentage change. Additionally, there is a question about the maximum difference of possible values above and below 20mm and their relation to 20mm. One suggestion for determining this uncertainty is using propagation of error.
usehn
Homework Statement
to get uncertainty of percentage change
Relevant Equations
((a-b)/b)*100
I have a measurement with uncertainties for two years. Say
Year 1 Rain : 100mm(80-120mm)
Year 2 Rain : 120mm(103-131mm).

Now I get the percentage change in rain in Year 2 w.r.t Year 1 as 20%. Is there a way to get the uncertainty associated with this percentage change?

usehn said:
I have a measurement with uncertainties for two years. Say
Year 1 Rain : 100mm(80-120mm)
Year 2 Rain : 120mm(103-131mm).

Now I get the percentage change in rain in Year 2 w.r.t Year 1 as 20%. Is there a way to get the uncertainty associated with this percentage change?
What is the maximum difference of possible set of values above 20mm and below 20mm. What are those relative to 20mm?

great thank you! Got it

Well, some folks misunderstand how to do that so it would be a good idea to post your conclusions / answer

Last edited:

## 1. What is the formula for calculating the uncertainty of a percentage change?

The formula for calculating the uncertainty of a percentage change is (Δp/p) x 100%, where Δp is the change in the original value and p is the original value.

## 2. How do I find the change in the original value for calculating the uncertainty of a percentage change?

To find the change in the original value, subtract the original value from the new value. For example, if the original value is 50 and the new value is 60, the change in the original value would be 60-50 = 10.

## 3. Can the uncertainty of a percentage change be negative?

No, the uncertainty of a percentage change cannot be negative. It represents the magnitude of the change and is always expressed as a positive value.

## 4. What is the significance of calculating the uncertainty of a percentage change?

Calculating the uncertainty of a percentage change is important because it gives us an idea of how confident we can be in the change that has occurred. It allows us to understand the range of possible values for the change in the original value.

## 5. How can I use the uncertainty of a percentage change in my research or experiments?

The uncertainty of a percentage change can be used in various scientific fields, such as physics, chemistry, and economics. It can help in making accurate predictions, comparing data, and assessing the reliability of results. It is also essential for drawing conclusions and making decisions based on experimental data.

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