Question

You want to test a new instrument for ammonia analysis in fog water (basic fog is associated with uncontrolled ammonia releases from waste lagoons containing agricultural waste from confined animal feedlot operations or CAFOs). First you have to check its operation against a standard reference solution of 100.00 micromolar ammonia. It reads 98.23, 88.16, 101.30, 101.47, 99.59 and 101.66 over six replicate measurements. Using α = 0.05 and a t-test, solve for if there is any evidence that the analysis is giving inaccurate results? Show your work. If the results are inaccurate you must express the bias (positive or negative) for the technique.

Answer 1

First we need to find the mean and SD of data. Following table shows the calculations:

	X	(X-mean)^2
	98.23	0.0289
	88.16	104.8576
	101.3	8.41
	101.47	9.4249
	99.59	1.4161
	101.66	10.6276
Total	590.41	134.7651

Sample size: n=6

Now,

Standard deviation:

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On the basis of sample evidence we cannot conclude that  the analysis is giving inaccurate results.