Refer to the California earthquake data in Section 3.8, found in the file CAQUAKES on the...

Refer to the California earthquake data in Section 3.8, found in the file CAQUAKES on the CD that came with your book. Mini tab programs are shown here to help with solving the problems.

a. Make a boxplot of the earthquake magnitudes. What is the approximate magnitude of the smallest outlier in the right-hand tail?

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b. It doesn’t make sense to talk about the median (or mean) magnitude of all California earthquakes in the period of time covered by our dataset. Why? Throughout the region specified, it seems reasonable to suppose that all quakes of magnitude 2.5 or greater are detected and correctly located. How many of these bigger quakes are there? Find their median magnitude.

MTB > Copy ' Mag ' ' Biggrmag ';

SUBC > Use ' Mag ' 2. 5 : 10 .

MTB > Describe ' BiggrMag '

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c. Can you discern an important difference in the magnitudes of California earthquakes before and after the time of the Yountville quake?

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d. Sometimes an earthquake triggers subsequent ones in its immediate vicinity-called aftershocks. Restrict the dataset to a small rectangle centered on the Yountville quake of magnitude 5.17. (A tenth of a degree of latitude and longitude in either direction would be appropriate.)

MTB > Copy ' Lat' ' Lon ' 'Mag' ' Ylat ' ' Ylon ' ' Ymag ';

SUBC > Use 'Lat ' 38. 28 : 38. 48.

MTB > Copy ' Ylat' ' Ylon ' ' Ymag ' ' Ylat ' ' Ylon ' 'YMag ';

SUBC > Use ' Ylon ' − 122. 513 : − 122. 313.

Explore this restricted dataset with an appropriate scatterplot (showing locations of the quakes), time series plot, and so on. Within the time span of our dataset and within this small rectangle, how many quakes occurred before the one of magnitude 5.17? After it? Were aftershocks located all around the initial quake or in a particular direction from it?