Question

Two analysts each made six determinations of the paracetamol content of the same batch of tablets. The results are shown below:
Analyst Paracetamol content % (m/m)
A 84.32 84.51 84.63 84.61 84.64 84.51
B 84.24 84.25 84.41 84.13 84.00 84.30

Questions:
We can measure of precision in terms of standard deviation. Which statement is TRUE for the precision of results of both analysts?
A) Analyst A is more precise than Analyst B
B) Analyst B is more precise than Analyst A
C) Analyst A and Analyst B have the same precision
D) Both analysts have incorrect analyses E) We need more information to conclude on this matter

If a seventh analysis (Trial 7) was made in the above paracetamol analysis and the result was 93.48, can this be considered as an outlier at 90% confidence? The critical value (Q) for seven (7) observations is 0.507.
A) It is an outlier, reject, and do not include in the computation of mean.
B) It is not an outlier, do not reject, and include in the computation of mean.

Answer 1

1. Calculate the standard deviation for each set and compare
2. Run the Dixon Q test for removing a single outlier and compare Qexpiment vs Q table value of 0.507. If Qexp > 0.507 the outlier may be removed.

Answer 2

Answer