use the Wilcoxon rank-sum test. Radiation in Baby Teeth ?Listed below are amounts of strontium-90 (in millibecquer-els, or mBq, per gram of calcium) in a simple random sample of baby teeth obtained from Pennsylvania residents and New York residents born after 1979 (based on data from “An Unexpected Rise in Strontium-90 in U.S. Deciduous Teeth in the 1990s,” by Mangano et a? cience of the Total Environment).? Use a 0.05 significance level to test the claim that the median amount of strontium-90 from Pennsylvania residents is the same as the median from New York residents. Pennsylvania 155 142 149 130 151 163 151 142 156 133 138 161 New York 133 140 142 131 134 129 128 140 140 140 137 143

Solution 8BSC Step 1 : Given, The amount of In the above example the data consists of the the amount of strontium-90 in a simple random sample of baby teeth obtained from Pennsylvania residents and New York born after 197921 , so the observations from the same population. Hence first requirement of the Wilcoxon Rank-Sum test satisfied. Each samples contains 12 values, it satisfies the second condition that the each sample should have the same median. Therefore, both the requirements of the Wilcoxon Sum-Rank test satisfies. Hypothesis : H 0 The median amount of strontium-90 from Pennsylvania residents is equal to the median of The median amount of strontium-90 from New York residents. H 1 The median amount of strontium-90 from Pennsylvania residents is not equal to the median of The median amount of strontium-90 from New York residents. Step 2 : We have 24 observations, based on the values we give ranks, if it is least value then rank will be 1 and next to the value will be 2 and so on. If there is a tie then mean of the values is the rank. Penns ylvani 142 155 149 130 151 a (15 163 (24) (21) (18) (3) (19.5) with ) rank 151 142 156 133 138 (19. (15 161 (23) (22) (5.5) (9) 5) ) New 133 140 York 142 131 134 (5.5 (11. 129 (2) with (15) (4) (7) ) 5) rank 140 140 128 140 137 (11. (11.5 143 (17) (1) (11.5) (8) 5) ) Ranks for of strontium-90 from Pennsylvania residents are 21, 15, 18, 3, 19.5, 24, 19.5, 15, 22, 5.5, 9, 23, The sum of the strontium-90 from Pennsylvania residents= 194.5