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