Gács and Ferraroli reported a method for monitoring the concentration of SO2 in
ID: 478310 • Letter: G
Question
Gács and Ferraroli reported a method for monitoring the concentration of SO2 in air. They compared their method to the standard method by analyzing urban air samples collected from a single location. Samples were collected by drawing air through a collection solution for 6 min.
Shown here is a summary of their results with SO2 concentrations reported in mL/m3:
standard method: 21.62 22.20 24.27 23.54 24.25 23.09 21.02
new method: 21.54 20.51 22.31 21.30 24.62 25.72 21.54
Using an appropriate statistical test determine whether there is any significant difference between the standard method and the new method at = 0.05. Report the average of the differences , standard deviation of the differences, t-exp, and the result for the null hypothesis as "accept" or "reject", and report whether there is a significant difference between the two methods as "yes" (there is a significant difference), or "no" (there is not a significant difference).
Explanation / Answer
t-Test
standard
new
21.62
21.5
22.20
20.51
24.27
22.31
23.54
21.3
24.25
24.62
23.09
25.72
21.02
21.54
-Test:
Two-Sample Assuming Equal Variances
standard
new
Mean
22.8557143
22.5057143
Variance
1.6323619
3.69032857
Observations
7
7
Pooled Variance
2.66134524
Hypothesized Mean Difference
0
df
12
t Stat
0.40137605
P(T<=t) one-tail
0.34759949
t Critical one-tail
1.78228674
P(T<=t) two-tail
0.69519898
t Critical two-tail
2.17881279
Results are given for both one-tailed and two-tailed tests.
If the value of P(T<=t) is less than t Stat, then the difference between the two data sets is signficant at the chosen confidence level.
there is no evidence for a difference between the new and standard methods.
standard
new
21.62
21.5
22.20
20.51
24.27
22.31
23.54
21.3
24.25
24.62
23.09
25.72
21.02
21.54
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