Statistical Problem in Analytical Chem

AI Thread Summary
The discussion revolves around determining whether a suspect value in a set of chloride concentrations in blood serum can be rejected at the 95% confidence level. The mean was calculated as 107.5, with a standard deviation of 4.65, and the t-value for 3 degrees of freedom was found to be 3.182. A confidence interval of 107.5 ± 7.40 was established, but the poster expressed uncertainty about the next steps. They also inquired about using Grubb's test as an alternative method for identifying outliers. The thread highlights the need for clarification on statistical methods in analytical chemistry.
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Homework Statement



The following set of analyses represent concentrations of chloride in blood serum (meq/L): 103,106,107,114. One value appears suspect. Determine if it can be rejected at the 95% confidence level.

Homework Equations


Mean

Standard Deviation:
standard-deviation-2.png


http://www.sjsu.edu/faculty/gerstman/StatPrimer/t-table.pdf"

Degrees of Freedom = n -1 (n in this case being 4)

Confidence Interval:
CI.jpg



The Attempt at a Solution



So I found the mean to 107.5, and the standard deviation to be 4.65 (If anyone wants to see how I did this, just let me know).

Then using the table, I found that t95 = 3.182 (using that there are 3 degrees of freedom)

Using the confidence interval formula, I calculated the answer to be 107.5 +/- 7.40.

I'm stuck from here and in fact have no idea if I even started this problem properly. PLEASE HELP :(
 
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Anyone? :( I'm super desperate
 


Actually -- would it be possible to simply use Grubb's test?
 
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