A nuclear plant was established in Hanford, Washington, in 1943. Over the years, a significant amount of strontium 90 and cesium 137 leaked into the Columbia River. In a study to determine how much this radioactivity caused serious medical problems for those who lived along the river, public health officials created an index of radioactive exposure for nine Oregon counties in the vicinity of the river. As a covariate, cancer mortality was determined for each of the counties (40). The results are given in the table in the next column. For the nine (xi, yi)€™s in the table,

Find the least squares straight line for these points. Also, construct the corresponding residual plot. Does it seem reasonable to conclude that x and y are linearly related?

Transcribed Image Text:

Σǐx, Σ x-: 289.4222 =41.56 =2894222 Σνί = 1.416.1 ΣΧΟϊ =7.439.37 Cancer Mortality per 100,000 County Index of Exposure Umatilla Morrow Gilliam Sherman Wasco Hood River Portland Columbia Clatsop 2.49 2.57 3.41 1.25 1.62 3.83 11.64 6.41 147.1 130.1 129.9 113.5 137.5 162.3 207.5 210.3