1. What is Percentage Deviation?

Percentage Deviation (PD) measures how much an observed value differs from a true or expected value, expressed as a percentage of the true value. It's commonly used in quality control, experimental sciences, and statistical analysis.

2. How Does the Calculator Work?

The calculator uses the Percentage Deviation formula:

Where:

• \( observed \) — The measured or experimental value
• \( true \) — The reference or expected value

Explanation: The formula calculates the absolute difference between observed and true values, divides by the true value, and converts to percentage.

3. Importance of Percentage Deviation

Details: Percentage deviation is crucial for assessing measurement accuracy, comparing experimental results to theoretical values, and evaluating quality control in manufacturing processes.

4. Using the Calculator

Tips: Enter both observed and true values. The true value cannot be zero (division by zero is undefined). Values can be positive or negative, but the deviation is always reported as a positive percentage.

5. Frequently Asked Questions (FAQ)

Q1: What's considered a good percentage deviation?
A: This depends on the field. In some lab measurements, <5% is excellent, while engineering tolerances might allow higher deviations.

Q2: How is this different from percentage error?
A: Percentage deviation and percentage error are often used interchangeably, though some fields make subtle distinctions between them.

Q3: Can percentage deviation be negative?
A: No, the absolute value in the formula ensures the result is always positive (0-100%).

Q4: What if my true value is zero?
A: The calculation becomes undefined. Consider using absolute deviation instead in such cases.

Q5: When should I use percentage deviation vs. absolute deviation?
A: Percentage deviation is better for comparing deviations across different scales, while absolute deviation shows the raw difference.