Fundamentals of Statistics contains material of various lectures and courses of H. Lohninger on statistics, data analysis and chemometrics......click here for more.

Exercise - Comparing two sample means

Measuring the concentration of strontium in drinking water in two different areas resulted in the following values:
 

Area 1 (20 sites)
concentrations in mg/l
  Area 2 (18 sites)
concentrations in mg/l
2.88 2.22 0.80 2.60 3.80
5.50 5.60 2.30 4.40 0.71
0.91 0.13 3.88 3.20 4.90
5.12 2.11 0.80 0.90 1.22
  5.54 4.99 4.31 3.52 3.28
4.20 2.33 5.80 3.03 3.77
3.81 2.65 2.36 2.05 2.47
4.22 4.89 3.17

Is there any significant difference in the strontium concentration between areas 1 and 2?  Try to find an answer with an error probability of 1 % and 5 %. Go to the  DataLab  in order to perform the necessary tests (the strontium data will be loaded automatically).

Last Update: 2012-10-08