a 18.26 Testosterone and obesity in adolescent males. Obesity in adult males is associated with lower levels of sex hormone. Example 17.2 described a study investigating a possible link between obesity and testosterone levels in adolescent males between the ages of 14 and 20 years. The study compared 25 obese adolescent males and 25 adolescent males with a healthy weight. Here are their plasma testosterone concentrations (in nanomoles per liter, nmol/l): Obese adolescent males 0.30 0.24 0.19 0.17 0.18 0.23 0.24 0.06 0.15 0.17 0.18 0.17 0.15 0.12 0.25 0.25 0.25 0.32 0.35 0.37 0.39 0.46 0.49 0.42 0.36 Adolescent males with a healthy weight 0.78 0.70 0.63 0.60 0.60 0.69 0.76 0.58 0.50 0.48 0.49 0.43 0.42 0.38 0.35 0.35 0.32 0.31 0.28 0.25 0.23 0.24 0.24 0.26 0.27 (a) Plot each data set to investigate the shapes of the distributions. Are the data appropriate for at procedure? (b) We suspect that obese adolescent males have a lower plasma testosterone level, on average. Do the data support this suspicion? Carry out the appropriate test and state your conclusion (c) Give a 95% confidence interval for the difference in mean plasma testosterone level between adolescent males who are obese and those who have a healthy weight. a TABLE 17.2 Glucose level (mg/dl) of 32 adolescents with type 1 diabetes under two treatment conditions, administered to each subject in random order Subject Control Bionic Subject Control Bionic Control Bionic Subject Control Bionic Subject 138 159 95 119 122 147 147 2 3 4 5 141 220 202 188 189 179 172 164 161 136 142 149 147 140 134 132 139 9 10 11 12 13 14 15 16 154 136 152 117 151 119 156 151 17 18 19 20 21 22 23 24 222 181 169 163 156 153 152 129 138 137 142 125 144 136 156 136 25 26 27 28 29 30 31 32 179 139 133 150 134 146 144 139 159 133 158 6 138 144 7 8 151 145 157