Q5(c). Paired t-test: carbon in coal by two methods
Certain coal samples were analyzed for their C content by two different analytical methods. Following results were obtained (in percentage) — samples 1 to 6: Method A 62.1, 60.8, 61.9, 60.9, 59.7, 61.4; Method B 62.8, 60.9, 62.2, 60.5, 59.9, 61.2. Decide by use of an appropriate t-test whether the different results of the two methods are significant at a confidence level of 90%. [t values for sample size 6, as printed: 90% 1.943; 95% 2.447; 99.9% 3.707; 99.5% 4.317]
Answer in brief
Paired t-test: D̄ = 0.117 %, sd = 0.387 %, tcalc = 0.74 < 1.943; the difference between the two methods is not significant at the 90 % confidence level.
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Coverspaired t-testsignificance testcomparison of methodsStudent's tconfidence level
All parts of Question 5
- 5(a) Polychromatic radiation and Beer's law5 marks
- 5(b) Analysis of a solid sample by ICP–MS: sequence of steps10 marks
- 5(c) Paired t-test: carbon in coal by two methods10 marks
- 5(d) Aniline point and Doctor test of petroleum products5 marks