Emphasis is placed on understanding the measurements, the operation of prescription balances, and the responsibility of the operator to carry out measurements as accurate as possible in order to avoid causing human casualties. The concept of measurement is explained first by an extensive description of accuracy versus precision of measured values. You can use the exact quantitative definition described in this chapter to classify measurements as accurate and/or precise, and you can further perfect your skills by solving the carefully selected multiple-choice, true or false, fill in the gaps, or computational problems. A connection to the pharmaceutical field is made through various examples that demonstrate that, as with all other applied sciences, appropriate units should accompany a meaningful measurement. It is also explained that measurements are obtained with laboratory instruments, and as such, they are always accompanied by an error. The magnitude of the error or uncertainty in a measurement is dependent not only on the analytical instrument but also on the skills and knowledge of the operator. The impact of accurate dose measurements in the livelihood of patients is also demonstrated, thus explicitly denoting that it is the responsibility of every scientist to be aware of measurement uncertainties.
KeywordsMeasurement Desired value Actual value Accuracy Precision Prescription balance Sensitivity requirement Error Percentage error Maximum allowable error Least allowable weight
Accuracy and precision of measurements. Description: (a) Characteristics of measurements. (b) Conducting measurements. (c) Reporting measurements. (d) Qualitative description of accuracy and precision for a collection and individual measurements. (e) Quantitative description of accuracy and precision for a collection and individual measurements. (f) Develop criteria based on the quantitative definition of accuracy and precision to select or prepare high quality compounded products (MP4 631105 kb)
Errors associated with measurements. Description: (a) Principles of operation of balances. (b) Definition of SR of a balance. (c) Formulas to calculate SR, error, % error, actual value, desired value, least allowable weight (LAW). (d) Absolute vs. relative error. (e) Calculate the LAW of drug within a maximum allowable error, in accord to federal regulations, and prepare high quality compounded products (MP4 599064 kb)