Statistical Problem in Analytical Chem

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SUMMARY

The discussion focuses on determining whether a suspect value in a set of chloride concentrations in blood serum can be rejected at the 95% confidence level. The mean concentration was calculated as 107.5 meq/L, with a standard deviation of 4.65. The t-value for 3 degrees of freedom was found to be 3.182, leading to a confidence interval of 107.5 +/- 7.40. The user inquired about the applicability of Grubb's test for outlier detection in this context.

PREREQUISITES
  • Understanding of basic statistics, including mean and standard deviation.
  • Familiarity with confidence intervals and t-distribution.
  • Knowledge of Grubb's test for outlier detection.
  • Ability to interpret statistical tables, specifically t-tables.
NEXT STEPS
  • Study the application of Grubb's test for identifying outliers in datasets.
  • Learn how to calculate confidence intervals using different statistical methods.
  • Explore the implications of degrees of freedom in hypothesis testing.
  • Review the use of t-distribution in small sample sizes for statistical analysis.
USEFUL FOR

Students in analytical chemistry, statisticians, and researchers involved in data analysis who need to understand statistical methods for outlier detection and confidence interval calculations.

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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 :(
 
Last edited by a moderator:
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Anyone? :( I'm super desperate
 


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

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