A researcher is interested in assessing whether an experimental drug is effectiv
ID: 3221175 • Letter: A
Question
A researcher is interested in assessing whether an experimental drug is effective in improving manual dexterity among people with multiple sclerosis. The researcher randomly selects 30 individuals and randomly assigns them to three groups. After five weeks of treatment a manual dexterity test is administered for which a higher score indicates greater manual dexterity.
Enter the following data in SPSS Using SPSS conduct a one-way ANOVA to investigate if the variation in treatment group means suggest a real difference in treatment means for the population. Alpha = .05 Complete post hoc comparisons of the groups using the Tukey HSD and the LSD methods. Include the SPSS output and interpret the results.
The assumptions for this test are:1)Scores are independent of each other 2)The data is normally distributed for all groups 3)The groups have equal variances
Answer the following questions:
1) Write the null hypothesis:
2) On the results, identify the following:
< > ratio for the group effect : _____ Explain what it means.
3)Sums of squares for the years of experience effect: _______Explain what it means.
Within groups: _____
4)Mean scores for those with significant experience in public health (10 hours and more) = _____
5)< > value for the years of experience effect = ______
6) Levene’s test results : F(, ) =_____, p =_____
7) Write the results in APA format
( SPSS output below)
Descriptives
Scores
N
Mean
Std. Deviation
Std. Error
95% Confidence Interval for Mean
Minimum
Maximum
Lower Bound
Upper Bound
1
10
7.00
1.700
.537
5.78
8.22
5
10
2
10
3.00
1.247
.394
2.11
3.89
1
5
3
10
4.00
1.491
.471
2.93
5.07
2
6
Total
30
4.67
2.249
.411
3.83
5.51
1
10
ANOVA
Scores
Sum of Squares
df
Mean Square
F
Sig.
Between Groups
86.667
2
43.333
19.500
.000
Within Groups
60.000
27
2.222
Total
146.667
29
Multiple Comparisons
Dependent Variable: Scores
(I) Groups
(J) Groups
Mean Difference (I-J)
Std. Error
Sig.
95% Confidence Interval
Lower Bound
Upper Bound
Tukey HSD
1
2
4.000*
.667
.000
2.35
5.65
3
3.000*
.667
.000
1.35
4.65
2
1
-4.000*
.667
.000
-5.65
-2.35
3
-1.000
.667
.307
-2.65
.65
3
1
-3.000*
.667
.000
-4.65
-1.35
2
1.000
.667
.307
-.65
2.65
LSD
1
2
4.000*
.667
.000
2.63
5.37
3
3.000*
.667
.000
1.63
4.37
2
1
-4.000*
.667
.000
-5.37
-2.63
3
-1.000
.667
.145
-2.37
.37
3
1
-3.000*
.667
.000
-4.37
-1.63
2
1.000
.667
.145
-.37
2.37
*. The mean difference is significant at the 0.05 level.
Scores
Groups
N
Subset for alpha = 0.05
1
2
Tukey HSDa
2
10
3.00
3
10
4.00
Descriptives
Scores
N
Mean
Std. Deviation
Std. Error
95% Confidence Interval for Mean
Minimum
Maximum
Lower Bound
Upper Bound
1
10
7.00
1.700
.537
5.78
8.22
5
10
2
10
3.00
1.247
.394
2.11
3.89
1
5
3
10
4.00
1.491
.471
2.93
5.07
2
6
Total
30
4.67
2.249
.411
3.83
5.51
1
10
Explanation / Answer
A researcher is interested in assessing whether an experimental drug is effective in improving manual dexterity among people with multiple sclerosis. The researcher randomly selects 30 individuals and randomly assigns them to three groups. After five weeks of treatment a manual dexterity test is administered for which a higher score indicates greater manual dexterity.
Enter the following data in SPSS Using SPSS conduct a one-way ANOVA to investigate if the variation in treatment group means suggest a real difference in treatment means for the population.
Here we have to test the hypothesis that,
H0 : The population means are equal
H1 : The population means are not equal.
Assume alpha = level of significance = 0.05
Here test statistic follows F-distribution.
In the output :
Test statistic (F) = 19.500
P-value = 0.000
P-value < alpha
Reject H0 at 5%level of significance.
Conclusion : Atleast one of the mean is differ than 0.
Sums of squares for the years of experience effect = 86.667
Now we have to see which treatment group differs.
SO we use post HOC test.
Here dependent variable is scores
Here we use Tukey's test for testing two means.
Here we have to test the hypothesis that,
H0 : Mui = Muj Vs H1 : Mui not= Muj
where Mui and Muj are the population means for ith and jth independent variable.
Here from the comparison we see that P-value for the pair 2 and 3 and pair 3 and 2 has P-value 0.307
Here P-value > alpha
Accept H0 at 5% level of significance.
Conclusion : The population mean for 2nd group and 3rd group may be same.
These pairs get insignificant result.
ANd the group 1,2 and group 1,3 have P-value is 0.000
P-value < alpha
Reject H0 at 5% level of significance.
Conclusion : group 1,2 and group 1,3 have different mean.
These pairs get significant result.
These are the conclusions from Tukey HSD test.
And the same conclusion from LSD.
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