Extremeness of a case is calculated by the difference between a case's value on the dependent variable and the variable's mean value.
Arguments
- lmobject
Object generated with
lm
Value
A dataframe with
- all variables in the linear model,
- absolute extremeness (absolute value of difference between variable score and mean value of variable),
- extremeness (difference between variable score and mean value of variable), which can be useful when the direction of extremeness is relevant.
The rows are ordered in decreasing order of the absolute extreme values.
Details
Calculating the absolute value of the difference between the cases' values and the variable's mean value is proposed by Seawright, Jason (2016): The Case for Selecting Cases That Are Deviant or Extreme on the Independent Variable. Sociological Methods & Research 45 (3): 493-525. (doi:10.1177/0049124116643556 )
Examples
df <- lm(mpg ~ disp + wt, data = mtcars)
extreme_on_y(df)
#> mpg disp wt abs. extremeness extremeness
#> Toyota Corolla 33.9 71.1 1.835 13.809375 13.809375
#> Fiat 128 32.4 78.7 2.200 12.309375 12.309375
#> Honda Civic 30.4 75.7 1.615 10.309375 10.309375
#> Lotus Europa 30.4 95.1 1.513 10.309375 10.309375
#> Cadillac Fleetwood 10.4 472.0 5.250 9.690625 -9.690625
#> Lincoln Continental 10.4 460.0 5.424 9.690625 -9.690625
#> Fiat X1-9 27.3 79.0 1.935 7.209375 7.209375
#> Camaro Z28 13.3 350.0 3.840 6.790625 -6.790625
#> Porsche 914-2 26.0 120.3 2.140 5.909375 5.909375
#> Duster 360 14.3 360.0 3.570 5.790625 -5.790625
#> Chrysler Imperial 14.7 440.0 5.345 5.390625 -5.390625
#> Maserati Bora 15.0 301.0 3.570 5.090625 -5.090625
#> Merc 450SLC 15.2 275.8 3.780 4.890625 -4.890625
#> AMC Javelin 15.2 304.0 3.435 4.890625 -4.890625
#> Dodge Challenger 15.5 318.0 3.520 4.590625 -4.590625
#> Merc 240D 24.4 146.7 3.190 4.309375 4.309375
#> Ford Pantera L 15.8 351.0 3.170 4.290625 -4.290625
#> Merc 450SE 16.4 275.8 4.070 3.690625 -3.690625
#> Merc 450SL 17.3 275.8 3.730 2.790625 -2.790625
#> Datsun 710 22.8 108.0 2.320 2.709375 2.709375
#> Merc 230 22.8 140.8 3.150 2.709375 2.709375
#> Merc 280C 17.8 167.6 3.440 2.290625 -2.290625
#> Valiant 18.1 225.0 3.460 1.990625 -1.990625
#> Toyota Corona 21.5 120.1 2.465 1.409375 1.409375
#> Hornet Sportabout 18.7 360.0 3.440 1.390625 -1.390625
#> Hornet 4 Drive 21.4 258.0 3.215 1.309375 1.309375
#> Volvo 142E 21.4 121.0 2.780 1.309375 1.309375
#> Mazda RX4 21.0 160.0 2.620 0.909375 0.909375
#> Mazda RX4 Wag 21.0 160.0 2.875 0.909375 0.909375
#> Merc 280 19.2 167.6 3.440 0.890625 -0.890625
#> Pontiac Firebird 19.2 400.0 3.845 0.890625 -0.890625
#> Ferrari Dino 19.7 145.0 2.770 0.390625 -0.390625