Robust SE

import pandas as pd
import statsmodels.api as sm
df = pd.DataFrame({'x': [1, 2, 3, 4, 5, 6], 'y': [1, 2, 2, 5, 5, 9]})
fit = sm.OLS(df['y'], sm.add_constant(df['x'])).fit()
rob = fit.get_robustcov_results(cov_type='HC1')
print('ols', fit.bse.round(3).to_dict())
print('hc1', pd.Series(rob.bse, index=fit.params.index).round(3).to_dict())

import pandas as pd
import statsmodels.api as sm
fit = sm.OLS([1, 2, 3], sm.add_constant([1, 2, 3])).fit(cov_type='HC1')
print(fit.bse.round(4).to_dict())

import pandas as pd
print(pd.Series([1, 2, 3]).std())

import pandas as pd
import statsmodels.api as sm
print(sm.OLS([1, 4, 9], sm.add_constant([1, 2, 3])).fit().bse.round(3).to_dict())