Engineering Metrology Multiple Choice Questions on “Type A Evaluation of Uncertainty”.
1. What do you mean by Type-A evaluation of uncertainty?
a) Involves a series of independent measurements of a quantity
b) Involves a series of dependent measurements of a quantity
c) Uncertainty which is characterized using an assumed probability distribution based on information available
d) Evaluated by judgment of available information
Answer: a
Clarification: Type-A evaluation of uncertainty is mainly based on repeated observations. Type-A evaluation of uncertainty involves making a series of a large number of independent quantity measurements.
2. What is used as an input estimate in Type-A evaluation of uncertainty?
a) Standard deviation
b) Arithmetic mean
c) Variance
d) Geometric mean
Answer: b
Clarification: The arithmetic mean is used as the input estimate in Type-A evaluation of uncertainty, and the standard deviation of the mean is used as the standard uncertainty. Those evaluation of standard uncertainty that is not a Type-A is a Type-B evaluation.
3. What is ANOVA in statistical analysis?
a) Analysis of variance
b) Analysis of various attributes of statistics
c) Analysis of non-observable variables
d) Assessment of various attributes of statistics
Answer: a
Clarification: Type-A evaluation of uncertainty is evaluated by using statistical analysis of series of observations scattered around some mean value which are associated with the ANOVA or analysis of variance.
4. Which is not used to evaluate Type-A uncertainty?
a) Arithmetic mean
b) Standard deviation
c) Sensitivity coefficient
d) Degree of freedom
Answer: c
Clarification: The best way to evaluate Type-A uncertainty data is by calculating the arithmetic mean, standard deviation or degree of freedom. Arithmetic mean is calculated first, followed by standard deviation and degree of freedom is calculated at last.
5. Which of the following is not treated as Type-A uncertainty?
a) Thermal stability
b) Noise
c) Repeatability
d) Resolution
Answer: d
Clarification: Here, the meaning of noise is the effect on a signal due to surrounding electrical interference and magnetic fields. Noise is treated as a random Type-A uncertainty. Other random Type-A uncertainty with a normal distribution is thermal stability and repeatability.
6. Which of the following statement is true about Type-A uncertainty?
Statement 1: Most of the systematic uncertainty is Type-A uncertainty.
Statement 2: Type-A uncertainties vary each and every time a measurement is made.
a) T, T
b) F, T
c) F, F
d) T, F
Answer: b
Clarification: Most of the systematic uncertainty is Type-B uncertainties while most of the random uncertainties are Type-A uncertainties. Every time when any measurement is made, Type-A uncertainty varies.
7. In which guide the symbols, terms and methods used for evaluating measurement uncertainty are described?
a) AUM
b) SUM
c) RUM
d) GUM
Answer: d
Clarification: The symbols, terms and methods used for evaluating measurement uncertainty are described in the GUM or Guide to the Expression of Uncertainty in Measurement, which was published in 1993 by the ISO (International Organization for Standardization).
8. What is the equation for experimental variance used in Type-A evaluation of uncertainty?
a) σ = √[(1/n-1) ∑ni=1 (xi-x’)].
b) σ = √[(1/n-1) ∑ni=1 (xi-x’)2].
c) σ = √[(1/n-1) ∑ni=1 (xi+x’)2].
d) σ = √[(1/n+1) ∑ni=1 (xi-x’)].
Answer: b
Clarification: Standard deviation is basically the measurement of the dispersion of a data set from its average. Formula is given by, σ = √[(1/n-1) ∑ni=1 (xi-x’)2], where x’ is arithmetic mean and is equal to [(1/n) ∑ni=1 (xi)].
9. How can Type-A uncertainties can be quantify?
a) Using quality transducer
b) Using stepper motor
c) Using LCR meter
d) Using conductivity meter
Answer: a
Clarification: Better quality transducer can be used to reduce Type-A and Type-B elemental uncertainties. Calibration can quantify Type-A elemental uncertainty, but not reduce it. Calibration can quantify as well as reduce the level of Type-B elemental uncertainty.
10. What is the value of the degree of freedom used in evaluation by Type-A method? (Where N is the number of independent measurements of quantity)
a) N
b) N+1
c) N-1
d) N+2
Answer: c
Clarification: The number of degrees of freedom used for evaluation is one less than the number of independent measurements of quantity i.e. if number of independent measurements are 100 then the degree of freedom is equal to (100-1).