ENCH 213 Study Guide - Quiz Guide: F-Test, Lead, Standard Deviation
5 Nov 2013
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Rejection/retention of outliers: grubbs test: compute the average, x , and standard deviation, s, gexp = xq x /s. Xq = questionable result: get gcrit from table 4-5, apply test: reject if gexp > gcrit (mean includes questionable value) The percentage of iron oxide, which gives paint its red color, found during analysis is as follows: 43. 15, 43. 81, 45. 71, 43. 23, What is the average percentage of the iron oxide in the paint sample: 43. 3, 43. 7, 43. 6. Q: a systematic error: can be discovered and corrected, arises from the limitations on the ability to make a physical measurement, is also known as an indeterminate error. Example 2: hg in mocked soil sample (small sample) data: % hg= 7. 5 6. 6: true = = 5. 86% hg. Is there a determinate error? tcalc = 8 |7. 5-5. 86|/6. 6 = 0. 548 tcrit for 7 degrees of freedom = 2. 365 at 95% confidence level tcalc < tcrit : no systematic error indicated.
