Question

 

Write a report on your answer to the following question.Your report need be typed using a text editor (such as Word document) with the relevant MINITAB outputs and plots copied and pasted onto the document. The answer should include
1.Description of the sample data including the study variables, design and study units
2.Details of the research question
3.The choice of the hypothesis test with justification
4.Exploratory data analysis including:
-Appropriate summary statistics from MINITAB-Appropriate plots from MINITAB with interpretation
-Any comments regarding trends in the data to support the research question
4.The null and alternative hypotheses of the hypothesis test
5.Details of the formal statistical analysisincluding:
-Informationon the test statisticandthe underlying distribution,
-Relevant MINITAB output for the test
-The test statistics, p-value and confidence intervals with appropriate interpretation
6.Test decision and conclusion
7. Assumptions of the hypothesis test including:
-Details of the assumptions
-Relevant MINITAB outputs with interpretation
-Conclusion
8.Summary of results and further comments if any.
ANALYSIS
All analysis must be undertaken in MINITAB

A study was conducted to investigate the concentration of hydrophobic organic substances such as Aldrin in the Wolf River in Tennessee. Aldrin concertation measurements (in nanograms per litre) were taken downstream of an abandoned dump site that had previously been used by the pesticide industry to dispose of its waste products. It was expected that Aldrin concentration might have a nonhomogeneous vertical distribution in the river because of differences in density between these compounds and water and because of the adsorption of these compounds on sediments, which could lead to higher concentrations on the bottom. As a results water samples from surface, mid depth and bottom of the river were collected at random and measured for Aldrin concentration.The following data were obtained:

Surface	Mid-depth	Bottom
3.08	5.17	4.81
3.58	6.17	5.71
3.61	6.26	4.9
4.31	4.26	5.35
4.35	3.17	5.26
4.7	3.76	6.26
3.67	4.76	3.76
4.87	4.9	8.07
5.47	6.57	8.79
4.35	5.17	7.3

At 5% level of significance, test fora difference in mean Aldrin concertation among the three depth levels;if there is a difference identify which depth levels have produced the difference

Answer 1

2)

3)
ANOVA one way, there are more than 2 levels of independent variable

4)
Ho: µ1 = µ2= µ3
Ha: at least one mean is different

5)

stat -> anova

5)
F-distribution with df1 = 2 and df2 = 27
TS = 5.90
p-value = 0.008
6)
since p-value < alpha
we reject the null hypothesis

8)

we conclude that there is significant difference in mean