a) accuracy is a measure of how close the measured value is to the true or accep

Question

a) accuracy is a measure of how close the measured value is to the true or accepted value. Precision is a measure of how reproducible the measurements are or how close or similar they are.

b) mean is the arithmetic average of a set of values. It is calculated by adding all the values and divine by the number of values.

Median is the middle value of a set of values

c) random errors are errors in measurement which are unpredictable or have unknown sources. They cannot be totally eliminated.

Systematic errors have a origin in the inaccurate method or measurement, ie the source of the error is inherent to he system. These can be elimnated to a large extent

d)The t test tests if there is an significance between two measurements obtained by two different techniques. The answer is obtained as yes or no. The q test is a test used to eliminate outlines from a range of values. That is it is used to determine the values that fall within a certain range

e) standardization is a term related to solutions while calibration is related to instruments or apparatus. Calibration is done to find out whether an instrument is working properly and is giving accurate values. Standardization is done to find out the strength of an unknown solution by using a solution of a known strength.

e) external standard are substances of known strength used as a comparasion for the sample. Internal standards are standards which are added to the sample and thus give the values under same set of conditions

g) detection limit is the lowest measurable value that can be reported with a certain confidence while sensitivity is the ability to distinguish between two very close values. It is the slope of the calibration curve

h) matrix modifier is a modifying agent ie it changes the properties of the preparation or the bulk material. Masking agent is an agent which reacts with a species which might cause interference in the measurement. Thus masking it's effects.

Explanation / Answer

9. Explain the differences between the following terms: (a) Accuracy and precision (b) Mean and median (c) Systematic and random error (d) t test and Q test (e) standardization and calibration (f) external and internal standard (g) sensitivity and detection limit (h) matrix modifier and masking agent

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