ANSWER :
The given information is
SPSS used to compare the 4 groups.
Ho: µ1= µ2= µ3= µ4
H1: At least one of the mean is different from the others
SPSS command
ONEWAY Severity BY Group
/STATISTICS DESCRIPTIVES
/MISSING ANALYSIS
/POSTHOC=TUKEY ALPHA(0.05).
SPSS output:
|
Descriptives
|
|
Severity
|
|
N
|
Mean
|
Std. Deviation
|
Std. Error
|
95% Confidence Interval for Mean
|
Minimum
|
Maximum
|
|
Lower Bound
|
Upper Bound
|
|
0mg
|
5
|
4.4000
|
1.81659
|
0.81240
|
2.1444
|
6.6556
|
2.00
|
6.00
|
|
250mg
|
5
|
3.8000
|
0.83666
|
0.37417
|
2.7611
|
4.8389
|
3.00
|
5.00
|
|
500mg
|
5
|
2.8000
|
0.83666
|
0.37417
|
1.7611
|
3.8389
|
2.00
|
4.00
|
|
1000mg
|
5
|
2.0000
|
1.58114
|
0.70711
|
0.0368
|
3.9632
|
0.00
|
4.00
|
|
Total
|
20
|
3.2500
|
1.55174
|
0.34698
|
2.5238
|
3.9762
|
0.00
|
6.00
|
|
ANOVA
|
|
Severity
|
|
Sum of Squares
|
df
|
Mean Square
|
F
|
Sig.
|
|
Between Groups
|
16.950
|
3
|
5.650
|
3.139
|
0.055
|
|
Within Groups
|
28.800
|
16
|
1.800
|
|
|
|
Total
|
45.750
|
19
|
|
|
|
Calculated F=3.139, P=0.055 which is > 0.05 level of
significance.
The null hypothesis is not rejected.
The data indicate there is no significant difference among the
four group means.
