Chapter 06.02 Exercise Question 25

6.2.25

Rising mercury levels due to industrial pollution is a recent concern. Many fish have high levels of mercury. Data were collected on random samples of tuna from 1991 to 2010 and are available in the fileTuna. Each row in the data set represents the mercury level of a different fish. With randomization techniques we are able to analyze any test statistic we desire. What if we wanted to look at whether there was a difference in the median values of mercury in the Yellowfin tuna compared to the Albacore tuna? Use the Multiple Means applet with the Median option to answer the following questions.

Is this an experiment or an observational study? Explain how you know.

a. Experiment: Researchers assigned variable values to the fish.

b. Observational study: Researchers did not assign variable values to the fish.

Identify the observational units.

a. Levels of mercury

b. Each fish

c. The two types of tuna

d. The years 1991 to 2010

Identify the explanatory and response variable. Also, identify whether each is quantitative or categorical.

a. Explanatory: mercury level (quantitative), response: type of tuna (categorical)

b. Explanatory: mercury level (categorical), response: type of tuna (quantitative)

c. Explanatory: type of tuna (quantitative), response: mercury level (categorical)

d. Explanatory: type of tuna (categorical), response: mercury level (quantitative)

Define (in words) the parameters of interest of this study.

a. The number of albacore tuna; the number of yellowfin tuna

b. The median mercury level in albacore tuna; the median mercury level in yellowfin tuna

State the null and alternative hypotheses in words.

a. Null: The median mercury level in albacore tuna is the same as in yellowfin tuna

Alt: The median mercury level in albacore tuna is greater than in yellowfin tuna.

b. Null: The median mercury level in albacore tuna is greater than in yellowfin tuna.

Alt: The median mercury level in albacore tuna is the same as in yellowfin tuna.

c. Null: The median mercury level in albacore tuna is the same as in yellowfin tuna

Alt: The median mercury level in albacore tuna is different from that in yellowfin tuna.

d. Null: The median mercury level in albacore tuna is different from that in yellowfin tuna.

Alt: The median mercury level in albacore tuna is the same as in yellowfin tuna.

What statistic will you use?

a. Difference in sample medians

b. Difference of sample means

Use an appropriate applet to carry out a simulation analysis. Report the p-value.

_____________________________________

the absolute tolerance is +/-0.02

Use the 2SD rule to determine a 95% confidence interval.

(________________________, __________________________)

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Chapter 06.02 Exercise Question 12

6.2.12

In a survey of introductory statistics students, an instructor asked her students how many flip-flops they have. Suppose that the intent is to study whether there is an association between number of flip-flops and a person's sex.

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