9. A laboratory manager decided to investigate the compatibility of four analyst

Question

9. A laboratory manager decided to investigate the compatibility of four analysts in their analysis of nitrite in wastewater using a standard method, which requires a wastewater sample must be analysed by the four analysts under the same experimental conditions using the same ion chromatograph. The results obtained are tabulated below. Analyst Replicates 10.2 10.4 10.0 2 11.2 10.9 10.9 10.3 10.4 10.7 4 10.5 10.7 10.4 2 Test whether the mean values obtained by the three analysts are statistically equal or there is a difference among them at the 95% confidence level If there is a statistical difference between the mean values, which mean value(s) is/are different. (a) (b)

Explanation / Answer

First of all I would like to correct your question with four Analysts Instead of Three..Because data set presented by Four Analysts..

Mean of 1 st Analyst is 10.2+10.4+10.0=30.6 : 30.6/3= 10.3

Mean of 2 nd Analyst is 11.2+10.9+10.9=33 : 33/3 =11

Mean of 3rd Analyst is 10.3+10.4+10.7 =31.4 : 31.4/3=24.26

Mean of 4th Analyst 10.5+10.7+10.4 =31.6 : 31.6/3=10.53

95 percent confidence level is saying is that if the analysis of Nitrite in waste water repeated over and over again, the results would match the results from the several analysts 95 percent of the time.

(a) So there is a difference in mean value of the above 4 analysts;Hence all the data is statastically not equal

(b) Third analyst mean value is different from other analyst mean values with a large difference..You can see in above calculation...

Thank you......

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