Instrumentation

# Define accuracy and precision

## What is the meaning of Measurement?

• Measurements is a process by which one can transform physical parameters into useful values.
• The process of measuring in which a characteristic of an object or system is evaluated in relation to a recognized standard unit.

## What is meant by Accuracy?

The degree to which a measured value is accurate in relation to a reference or known value is referred as accuracy.

## Define Resolution

• It is described as the smallest increment in the measured value that the instrument can detect with certainty.
• Every instrument’s resolution is determined by its least count.

## What is Range?

The range of the instrument is defined as the lower and upper limits of the instrument’s operating range for measuring, indicating or recording the measured variable

## Define Span

The algebraic difference between the upper and lower range values is termed as the span of the instrument.

## What is Precision?

The precision is defined as degree to which two or more measurements is matched with each other. A measurement is said to high precise but need not to be accurate.

## Define Measurement uncertainty.

The range of potential values within which the true value of the measurement presents is referred to as uncertainty in this context.

## What is meant by Histogram tool? Describe with example.

• The histogram is a frequent graphing tool. It is used to display representation of discrete or continuous data that have been interval-scaled.
• It is widely applied to conveniently represent the key features of the data distribution.
• A histogram is a graphic representation of data that has been measured. This curve shows the frequency distribution.

Example: Measuring length data

## Define Sensitivity.

Sensitivity is defined as the ratio of the change in the output to the change in the input for a small time.

## How Dispersion is measured from mean.

The degrees to which the values are distributed around the center value is used to measurement of dispersion from the mean. It is an indication of the data’s degree of precision and regularity.

## Difference between accuracy, repeatability & resolution

Accuracy – Degree of conformity of a measurement to a standard or known value.

Repeatability – The closeness of agreement between several successive measurements

Resolution – The smallest degree of movement that as scale can detect.

### Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe

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