Robust Regressions 163

TABLE 8.1 (Continued)

Issue

Leverage

Point

Issue

#

Leverage

Point

Issue

#

Leverage

Point

Issue

#

Leverage

Point

121 0.015754 141 0.157105 161 0.025706 181 0.041400

122 0.020207 142 0.020563 162 0.014594 182 0.013532

123 0.023941 143 0.018518 163 0.014276 183 0.011638

124 0.033133 144 0.016334 164 0.018527 184 0.015537

125 0.021344 145 0.016663 165 0.008675 185 0.009148

126 0.007491 146 0.018707 166 0.020882 186 0.008451

127 0.009683 147 0.011602 167 0.012834 187 0.020417

128 0.011631 148 0.016474 168 0.062460 188 0.023978

129 0.008184 149 0.054354 169 0.031092 189 0.023629

130 0.067155 150 0.020168 170 0.012731 190 0.018335

131 0.015243 151 0.019845 171 0.010213 191 0.012962

132 0.009928 152 0.014368 172 0.015083 192 0.025442

133 0.020009 153 0.008312 173 0.010233 193 0.034161

134 0.015243 154 0.010802 174 0.014593 194 0.026897

135 0.014425 155 0.010850 175 0.019872 195 0.014917

136 0.010076 156 0.011566 176 0.011204 196 0.037224

137 0.013824 157 0.012781 177 0.010866 197 0.019013

138 0.013863 158 0.013124 178 0.010313 198 0.022461

139 0.014560 159 0.017243 179 0.008397 199 0.015419

140 0.032351 160 0.011670 180 0.012101 200 0.012067

Leverage Point: In robust regressions, signals that the corresponding observations
might have a decisive influence on the estimation of the regression parameters.

TABLE 8.2 Robust Estimates of Parameters Using

Huber and Tukey Weighting Functions

Coefficient Huber Tu key

β 0 157.0116 157.0138

β 1 61.2781 61.2776

β 2 –13.2054 –13.2052

β 3 –90.8871 –90.8871