Uncertainties in Measurement

What is uncertainty?

• Defines the net effect of the error. It quantifies the doubt that exists in any reported value of the measurement.

• Desribes the scatter or the variability of the measurement values mode.

• Difference between the "true" value and the measured value

Suppose you want to measure the thickness of this book. What unit of measurement will you use?Which of the instrument/equipment is the best to use?

• Measuring tape

• Ruler

• Vernier caliper

How does accuracy differ from precision?

• Accuracy is the closeness of a measurement to the true or accepted value.

• Accuracy is how close the measurement to each other

• Precision is the degree of agreement between succesive measurement using a given instrument

What is true about Analyzing the accuracy and precision of a measurement?

• to determine the validity of the data obtained in an experiment

• Accuracy and Precision are the same thing so you don't have to ananalyze

• You can determine accuracy without the true value

How do you analyze the accuracy and precision in measurements?

• If the exhibit high accuracy

• if the data exhibit high accuracy and high precision

• by using ruler,vernier caliper and meter stick

When do you say that a given set of measurements is high in precision but low accuracy?

How do we describe a good measurement?

What is the difference between the arithmetic mean and the standard deviation?

Choose suitable instrument to measure time?

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A quality denoting the closeness of agreement (consistency) between values obtained by repeated measurement. It is influenced by random effects and can be expressed numerically.

• Repeatability

• Precision

• Uncertainty

• Resolution