Question

Q1; Explain briefly the difference between Shifts and Trends in systematic error (SE).

Q2:When do we need to do Methods Validation studies?

Q3: Write brief note on errors that cause a method to be out of control.

Q4: A new test was developed to detect the presence of Group A streptococcus in throat swabs. The manufacturer testes the kit on 600 pediatric patients with presumptive diagnoses of Group A streptococcus. 475 patients tested positive for Group A streptococcus; of these 475, 460 were verified by culture to be positive. 125 children tested negative by the kit; of these, 20 were positive by group A streptococcus by culture. What is the diagnostic sensitivity of this new kit?

Answer 1

1. A shift is a sudden change of values from one level of the control chart to another. A common cause of a shift is failure to recalibrate when changing lot numbers of reagents during an analytical run.

A trend is a continuous movement of values in one direction over six or more analytical runs.

2. Validation is done to assure that the processes will produce consistent and repeatable results within the predetermined specifications. Validation is needed as it verifies whether the quality standards and compliance are being met by the product in real time, which is really important in every pharmaceutical facility.

3.

The measurement error is defined as the difference between the true or actual value and the measured value. The true value is the average of the infinite number of measurements, and the measured value is the precise value.

The error may arise from the different source and are usually classified into the following types. These types are

Gross Errors

Systematic Errors

Random Errors

Gross Errors

The gross error occurs because of the human mistakes. For examples consider the person using the instruments takes the wrong reading, or they can record the incorrect data. Such type of error comes under the gross error. The gross error can only be avoided by taking the reading carefully.

Systematic Errors

The systematic errors are mainly classified into three categories.

Instrumental Errors

Environmental Errors

Observational Errors

Random errors:- the error which is caused by the sudden change in the atmospheric condition, such type of error is called random error. these type of error remain even after the removal of the systematic error. hence such type of error is called as random errors.

Minimising errors:

These errors can be minimised by using proper instruments, improving the experimental procedure and removing personal bias.