The accuracy and precision of an elemental analyzer (CHN) was tested with a reference sample that contains 11.70% carbon. The analysis was performed in quintuplicate providing the following results: 11.50; 11.87; 11.43; 12.25 and 11.20%. Equipment within specifications must have a coefficient of variation (CV) of less than 3% and have the reference value included in the 95% confidence interval. Based on this information, check the correct statement (s) below: A. The mean, standard deviation and number of degrees of freedom involved in this analysis are: 11.65; 0.41 and 5. B. As the reference value is not included in the confidence interval, we can conclude that the equipment is out of calibration (inaccurate). C. The accuracy of the equipment is assessed by including the reference value in the 95% confidence interval. D. From the variation coefficient value obtained, we can say that the equipment is not within specifications. E. The mean and 95% confidence interval are 11.65 ± 0.51% (m / m).
The accuracy and precision of an elemental analyzer (CHN) was tested with a reference sample that contains 11.70% carbon. The analysis was performed in quintuplicate providing the following results: 11.50; 11.87; 11.43; 12.25 and 11.20%. Equipment within specifications must have a coefficient of variation (CV) of less than 3% and have the reference value included in the 95% confidence interval. Based on this information, check the correct statement (s) below:
A. The
B. As the reference value is not included in the confidence interval, we can conclude that the equipment is out of calibration (inaccurate).
C. The accuracy of the equipment is assessed by including the reference value in the 95% confidence interval.
D. From the variation coefficient value obtained, we can say that the equipment is not within specifications.
E. The mean and 95% confidence interval are 11.65 ± 0.51% (m / m).
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