7.42 Index of Biotic Integrity. The Ohio Environmental Protection Agency used the Index of Biotic Integrity (IBI) to measure the biological condition or health of an aquatic region. The IBI is the sum of metrics which measure the
presence, abundance, and health of fish in the region.
(Higher values of the IBI correspond to healthier fish populations.) Researchers collected IBI measurements for sites
located in different Ohio river basins. (Journal of Agricultural, Biological, and Environmental Sciences, June 2005.)
1mA - mB)
1mB - mC)
1yA - yB2 1yB - yC2
yA yB yC
Summary data for two river basins, Muskingum and Hocking, are given in the table. Use a 90% confidence interval to
compare the mean IBI values of the two river basins.
Standard
River Basin Sample Size Mean Deviation
Muskingum 53 .035 1.046
Hocking 51 .340 .960