A new emergency procedure was developed to reduce the time that is required to f
ID: 3301262 • Letter: A
Question
A new emergency procedure was developed to reduce the time that is required
to fix a certain manufacturing problem. Past data under the old system were available
(n = 25). The staff was trained under the new procedure, and the response times for
the next 15 occurrences of this manufacturing problem were recorded.
Old Procedure
4.3 6.5 4.6 4.3 6.4 4.8 5.1 6.8 4.9 4.5 5.1 7.3 3.3
5.0 4.6 7.0 5.1 3.8 5.2 4.1 5.7 4.6 5.9 3.1 6.2
New Procedure
6.2 4.0 3.3 4.5 2.3 3.0 3.2 6.0
3.7 4.5 5.3 4.0 5.4 4.3 3.8
Compare the response times under the old and the new procedure. Are there differences in
the mean responses? Discuss using appropriate graphs, summary statistics, and statistical
tests. Would you switch to the new procedure
Explanation / Answer
Solution: we have to check significant difference between two means.
We use t test for two means.
Null hypothesis: H0: There is no significant difference between two means.
Alternative hypothesis: Ha: There is significant difference between two means.
From given data, descriptive statistics are
Group
Group One
Group Two
Mean
5.128
4.233
SD
1.112
1.115
SEM
0.222
0.288
N
25
15
Using t test,
t = 2.4615
df = 38
standard error of difference = 0.363
The two-tailed P value equals 0.0185
By conventional criteria, this difference is considered to be statistically significant.
Conclusion: There is difference in mean responses.
Group
Group One
Group Two
Mean
5.128
4.233
SD
1.112
1.115
SEM
0.222
0.288
N
25
15
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