Which data design? Each situation described in Excersises 18.1 to 18.4 requires

Question

Which data design? Each situation described in Excersises 18.1 to 18.4 requires inference about a mean or means. Identify each as involving (1) a single sample, (2) matched pain, or (3) two independent samples. The procedures of Chapter 17 apply to designs (1) and (2). We are about to learn procedures for (3). Acid rain. You contact a random sample of 24 hydrological stations in California and obtain data on the acidity of rainwater collected at each station in 2000 and in 2010. Acidity a measured by pH on a scale of 0 to 14 (the pH of distilled water is 7.0). You want to estimate the average change in acidity of rainwater in California between the Year 2000 and the year 2010. Agricultural pests. Agricultural pests can be controlled to some extent either by using pesticides to kill them or by introducing a large number of sterilized males to diminish the species' reproductive potential. Ten large corn field at harvest time is then compared for the two treatments. Chemical analysis. To check a new analytical method, a chemist obtains a reference specimen of known concentration from the National Institute of Standards and Technology. She then makes 20 measurements of the concentration of this specimen with the new method and checks for bias by comparing the mean result with the known concentration

Explanation / Answer

18.1

In this case we are using the same stations to record data in 2000 and 2010 , thus this data design is an example of matched pairs.

18.2

Here we are using different treatments in different fields, thus this is an example of two independent samples.

18.3

Here the comparision is done for the same sample before and after the treatment, thus this is a case of matched pairs.

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