Which of the following statements is incorrect?

Options

A. Every measurement by measuring instrument has some error.
B. A measurement can have more accuracy but less precision and vice versa.
C. Every calculated quantity that is based on measured values has some error.
D. The magnitude of the difference between the true value of the quantity and the individual measurement value is called the relative error of the measurement.

Explanation

To determine which statement is incorrect, let's analyze each statement one by one:

1. **Every measurement by measuring instrument has some error.**
- This statement is true. All measurements are subject to some degree of uncertainty or error due to limitations in the measuring instrument, environmental factors, and human error.

2. **A measurement can have more accuracy but less precision and vice versa.**
- This statement is also true. Accuracy refers to how close a measurement is to the true value, while precision refers to the consistency of repeated measurements. It is possible to have a measurement that is accurate but not precise, and vice versa.

3. **Every calculated quantity that is based on measured value has some error.**
- This statement is true as well. Any calculated value derived from measurements will inherit the errors from the individual measurements, leading to an overall error in the calculated result.

4. **The magnitude of the difference between the true value of the quantity and the individual measurement value is called the relative error of the measurement.**
- This statement is incorrect. The correct term for the magnitude of the difference between the true value and the individual measurement is called the **absolute error**. The relative error is actually the absolute error divided by the true value, often expressed as a percentage.

Based on this analysis, the incorrect statement is:

**The magnitude of the difference between the true value of the quantity and the individual measurement value is called the relative error of the measurement.**

### Summary of the Incorrect Statement:
- The statement incorrectly defines relative error; it should define absolute error instead.