Разница в линейной регрессии с использованием Statsmodels между версией Patsy и версией Dummy-списков
Если вы хотите преобразовать все *.ipynb файлы из текущего каталога в сценарий python, вы можете запустить команду следующим образом:
jupyter nbconvert --to script *.ipynb
0
задан NuValue 19 February 2019 в 12:39
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1 ответ
Причина, по которой результаты не совпадают, заключается в том, что Statsmodels выполняет предварительный отбор прогнозирующих переменных в зависимости от высокой мультиколлинеарности.
Точно такие же результаты достигаются путем описания описанной регрессии и определения отсутствующих переменных:
deletex = [
'make_alfa-romero',
'fuel_system_1bbl',
'engine_type_dohc',
'num_of_doors_four'
]
df_num.drop( deletex, axis = 1, inplace = True)
df_num = df_num[df_num.columns].apply(pd.to_numeric, errors='coerce', axis = 1)
X = df_num.drop('price', axis = 1)
y = df_num.price.values
Xc = sm.add_constant(X) # Adds a constant to the model
random.seed(1234)
linear_regression = sm.OLS(y, Xc)
linear_regression.fit().summary()
, который печатает результат:
OLS Regression Results
==============================================================================
Dep. Variable: y R-squared: 0.894
Model: OLS Adj. R-squared: 0.868
Method: Least Squares F-statistic: 35.54
Date: Thu, 21 Feb 2019 Prob (F-statistic): 5.24e-62
Time: 18:16:08 Log-Likelihood: -1899.7
No. Observations: 205 AIC: 3879.
Df Residuals: 165 BIC: 4012.
Df Model: 39
Covariance Type: nonrobust
======================================================================================
coef std err t P>|t| [0.025 0.975]
--------------------------------------------------------------------------------------
const 1.592e+04 1.21e+04 1.320 0.189 -7898.396 3.97e+04
bore 3993.4308 1373.487 2.908 0.004 1281.556 6705.306
compression_ratio -1200.5665 460.681 -2.606 0.010 -2110.156 -290.977
height -80.7141 146.219 -0.552 0.582 -369.417 207.988
peak_rpm -0.5903 0.790 -0.747 0.456 -2.150 0.970
make_audi 6519.7045 2371.807 2.749 0.007 1836.700 1.12e+04
make_bmw 1.427e+04 2292.551 6.223 0.000 9740.771 1.88e+04
make_chevrolet -571.8236 2860.026 -0.200 0.842 -6218.788 5075.141
make_dodge -1186.3430 2261.240 -0.525 0.601 -5651.039 3278.353
make_honda 2779.6496 2891.626 0.961 0.338 -2929.709 8489.009
make_isuzu 3098.9677 2592.645 1.195 0.234 -2020.069 8218.004
make_jaguar 1.752e+04 2416.313 7.252 0.000 1.28e+04 2.23e+04
make_mazda 306.6568 2134.567 0.144 0.886 -3907.929 4521.243
make_mercedes-benz 1.698e+04 2320.871 7.318 0.000 1.24e+04 2.16e+04
make_mercury 2958.1002 3605.739 0.820 0.413 -4161.236 1.01e+04
make_mitsubishi -1188.8337 2284.697 -0.520 0.604 -5699.844 3322.176
make_nissan -1211.5463 2073.422 -0.584 0.560 -5305.405 2882.312
make_peugot 3057.0217 4255.809 0.718 0.474 -5345.841 1.15e+04
make_plymouth -894.5921 2332.746 -0.383 0.702 -5500.473 3711.289
make_porsche 9558.8747 3688.038 2.592 0.010 2277.044 1.68e+04
make_renault -2124.9722 2847.536 -0.746 0.457 -7747.277 3497.333
make_saab 3490.5333 2319.189 1.505 0.134 -1088.579 8069.645
make_subaru -1.636e+04 4002.796 -4.087 0.000 -2.43e+04 -8456.659
make_toyota -770.9677 1911.754 -0.403 0.687 -4545.623 3003.688
make_volkswagen 406.9179 2219.714 0.183 0.855 -3975.788 4789.623
make_volvo 5433.7129 2397.030 2.267 0.025 700.907 1.02e+04
fuel_system_2bbl 2142.1594 2232.214 0.960 0.339 -2265.226 6549.545
fuel_system_4bbl 464.1109 3999.976 0.116 0.908 -7433.624 8361.846
fuel_system_idi 1.991e+04 6622.812 3.007 0.003 6837.439 3.3e+04
fuel_system_mfi 3716.5201 3936.805 0.944 0.347 -4056.488 1.15e+04
fuel_system_mpfi 3964.1109 2267.538 1.748 0.082 -513.019 8441.241
fuel_system_spdi 3240.0003 2719.925 1.191 0.235 -2130.344 8610.344
fuel_system_spfi 932.1959 4019.476 0.232 0.817 -7004.041 8868.433
engine_type_dohcv -1.208e+04 4205.826 -2.872 0.005 -2.04e+04 -3773.504
engine_type_l -4833.9860 3763.812 -1.284 0.201 -1.23e+04 2597.456
engine_type_ohc -4038.8848 1213.598 -3.328 0.001 -6435.067 -1642.702
engine_type_ohcf 9618.9281 3504.600 2.745 0.007 2699.286 1.65e+04
engine_type_ohcv 3051.7629 1445.185 2.112 0.036 198.323 5905.203
engine_type_rotor 1403.9928 3217.402 0.436 0.663 -4948.593 7756.579
num_of_doors_two -419.9640 521.754 -0.805 0.422 -1450.139 610.211
==============================================================================
Omnibus: 65.777 Durbin-Watson: 1.217
Prob(Omnibus): 0.000 Jarque-Bera (JB): 399.594
Skew: 1.059 Prob(JB): 1.70e-87
Kurtosis: 9.504 Cond. No. 3.26e+05
==============================================================================
Warnings:
[1] Standard Errors assume that the covariance matrix of the errors is correctly specified.
[2] The condition number is large, 3.26e+05. This might indicate that there are
strong multicollinearity or other numerical problems.
Результаты, которые полностью равны первый вызов с Statsmodels:
random.seed(1234)
lm_python = smf.ols('price ~ make + fuel_system + engine_type + num_of_doors + bore + compression_ratio + height + peak_rpm + 1', data = df)
lm_python.fit().summary()
OLS Regression Results
==============================================================================
Dep. Variable: price R-squared: 0.894
Model: OLS Adj. R-squared: 0.868
Method: Least Squares F-statistic: 35.54
Date: Thu, 21 Feb 2019 Prob (F-statistic): 5.24e-62
Time: 18:17:37 Log-Likelihood: -1899.7
No. Observations: 205 AIC: 3879.
Df Residuals: 165 BIC: 4012.
Df Model: 39
Covariance Type: nonrobust
=========================================================================================
coef std err t P>|t| [0.025 0.975]
-----------------------------------------------------------------------------------------
Intercept 1.592e+04 1.21e+04 1.320 0.189 -7898.396 3.97e+04
make[T.audi] 6519.7045 2371.807 2.749 0.007 1836.700 1.12e+04
make[T.bmw] 1.427e+04 2292.551 6.223 0.000 9740.771 1.88e+04
make[T.chevrolet] -571.8236 2860.026 -0.200 0.842 -6218.788 5075.141
make[T.dodge] -1186.3430 2261.240 -0.525 0.601 -5651.039 3278.353
make[T.honda] 2779.6496 2891.626 0.961 0.338 -2929.709 8489.009
make[T.isuzu] 3098.9677 2592.645 1.195 0.234 -2020.069 8218.004
make[T.jaguar] 1.752e+04 2416.313 7.252 0.000 1.28e+04 2.23e+04
make[T.mazda] 306.6568 2134.567 0.144 0.886 -3907.929 4521.243
make[T.mercedes-benz] 1.698e+04 2320.871 7.318 0.000 1.24e+04 2.16e+04
make[T.mercury] 2958.1002 3605.739 0.820 0.413 -4161.236 1.01e+04
make[T.mitsubishi] -1188.8337 2284.697 -0.520 0.604 -5699.844 3322.176
make[T.nissan] -1211.5463 2073.422 -0.584 0.560 -5305.405 2882.312
make[T.peugot] 3057.0217 4255.809 0.718 0.474 -5345.841 1.15e+04
make[T.plymouth] -894.5921 2332.746 -0.383 0.702 -5500.473 3711.289
make[T.porsche] 9558.8747 3688.038 2.592 0.010 2277.044 1.68e+04
make[T.renault] -2124.9722 2847.536 -0.746 0.457 -7747.277 3497.333
make[T.saab] 3490.5333 2319.189 1.505 0.134 -1088.579 8069.645
make[T.subaru] -1.636e+04 4002.796 -4.087 0.000 -2.43e+04 -8456.659
make[T.toyota] -770.9677 1911.754 -0.403 0.687 -4545.623 3003.688
make[T.volkswagen] 406.9179 2219.714 0.183 0.855 -3975.788 4789.623
make[T.volvo] 5433.7129 2397.030 2.267 0.025 700.907 1.02e+04
fuel_system[T.2bbl] 2142.1594 2232.214 0.960 0.339 -2265.226 6549.545
fuel_system[T.4bbl] 464.1109 3999.976 0.116 0.908 -7433.624 8361.846
fuel_system[T.idi] 1.991e+04 6622.812 3.007 0.003 6837.439 3.3e+04
fuel_system[T.mfi] 3716.5201 3936.805 0.944 0.347 -4056.488 1.15e+04
fuel_system[T.mpfi] 3964.1109 2267.538 1.748 0.082 -513.019 8441.241
fuel_system[T.spdi] 3240.0003 2719.925 1.191 0.235 -2130.344 8610.344
fuel_system[T.spfi] 932.1959 4019.476 0.232 0.817 -7004.041 8868.433
engine_type[T.dohcv] -1.208e+04 4205.826 -2.872 0.005 -2.04e+04 -3773.504
engine_type[T.l] -4833.9860 3763.812 -1.284 0.201 -1.23e+04 2597.456
engine_type[T.ohc] -4038.8848 1213.598 -3.328 0.001 -6435.067 -1642.702
engine_type[T.ohcf] 9618.9281 3504.600 2.745 0.007 2699.286 1.65e+04
engine_type[T.ohcv] 3051.7629 1445.185 2.112 0.036 198.323 5905.203
engine_type[T.rotor] 1403.9928 3217.402 0.436 0.663 -4948.593 7756.579
num_of_doors[T.two] -419.9640 521.754 -0.805 0.422 -1450.139 610.211
bore 3993.4308 1373.487 2.908 0.004 1281.556 6705.306
compression_ratio -1200.5665 460.681 -2.606 0.010 -2110.156 -290.977
height -80.7141 146.219 -0.552 0.582 -369.417 207.988
peak_rpm -0.5903 0.790 -0.747 0.456 -2.150 0.970
==============================================================================
Omnibus: 65.777 Durbin-Watson: 1.217
Prob(Omnibus): 0.000 Jarque-Bera (JB): 399.594
Skew: 1.059 Prob(JB): 1.70e-87
Kurtosis: 9.504 Cond. No. 3.26e+05
==============================================================================
Существует необходимость проверки соответствия в прогнозирующих переменных, поскольку pd.get_dummies осуществляет обширное получение всех фиктивных переменных, а Statsmodels применяет уровни N-1. внутри категориальной переменной выбора.
0
ответ дан NuValue 19 February 2019 в 12:39
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