Answer:
Reject the Null ;
0.928
Step-by-step explanation:
Given the data: 2, 4, 3, 5, 1, 1, 4
Sample mean = (2 + 4 + 3 + 5 + 1 + 1 + 4) / 7 = 2.857
Standard deviation, s = 1.57 ( using calculator)
The hypothesis :
H0 : μ = 1.4
H1 : μ ≠ 1.4
Since sample size is small, use T test
Test statistic :
Tstatistic = (x - μ) / s/sqrt(n)
Tstatistic = (2.857 - 1.4) / 1.57/sqrt(7)
Tstatistic = 1.457 / 0.593 = 2.455
Two tailed test at α = 0.05
Tcritical at df = 7-1 = 6 ; α = 0.05 = 2.447
Tstatistic > Tcritical ; reject the null
Since ;
2.455 > 2.447 ; we reject the null ;
There is significam evidence that Number of complaints has changed.
Effect size ;
d = (x - μ) / s
d = (2.857 - 1.4) / 1.57
d = 1.457 / 1.57
d = 0.928
