deaths per 1000 live births) for certain selected countries before World
War II. Calculate the 95% confidence interval for Pearson’s correlation
coe‰cient between the net food supply and the infant mortality rate.4.32 In an assay of heparin, a standard preparation is compared with a test
preparation by observing the log clotting times (y, in seconds) of blood
containing di¤erent doses of heparin (xis the log dose) (Table E4.32).
Replicate readings are made at each dose level. Calculate separately for
the standard preparation and the test preparation the 95% confidence
interval for Pearson’s correlation coe‰cient between the log clotting
times and log dose.
TABLE E4.32
Log Clotting Times
Standard Test Log Dose
1.806 1.756 1.799 1.763 0.72
1.851 1.785 1.826 1.832 0.87
1.954 1.929 1.898 1.875 1.02
2.124 1.996 1.973 1.982 1.17
2.262 2.161 2.140 2.100 1.324.33 There have been times when the city of London, England, experienced
periods of dense fog. Table E4.33 shows such data for a 15-day very
severe period which include the number of deaths each day (y), the mean
atmospheric smoke (x 1 , in mg/m^3 ), and the mean atmospheric sulfur
dioxide content (x 2 , in ppm). Calculate the 95% confidence interval for
Pearson’s correlation coe‰cient between the number of deaths (y) and
TABLE E4.33
Number of Deaths Smoke Sulfur Dioxide
112 0.30 0.09
140 0.49 0.16
143 0.61 0.22
120 0.49 0.14
196 2.64 0.75
294 3.45 0.86
513 4.46 1.34
518 4.46 1.34
430 1.22 0.47
274 1.22 0.47
255 0.32 0.22
236 0.29 0.23
256 0.50 0.26
222 0.32 0.16
213 0.32 0.16EXERCISES 185