def test_cov_cluster_2groups():
#comparing cluster robust standard errors to Peterson
#requires Petersen's test_data
#http://www.kellogg.northwestern.edu/faculty/petersen/htm/papers/se/test_data.txt
import os
cur_dir = os.path.abspath(os.path.dirname(__file__))
fpath = os.path.join(cur_dir,"test_data.txt")
pet = np.genfromtxt(fpath)
endog = pet[:,-1]
group = pet[:,0].astype(int)
time = pet[:,1].astype(int)
exog = add_constant(pet[:,2], prepend=True)
res = OLS(endog, exog).fit()
cov01, covg, covt = sw.cov_cluster_2groups(res, group, group2=time)
#Reference number from Petersen
#http://www.kellogg.northwestern.edu/faculty/petersen/htm/papers/se/test_data.htm
bse_petw = [0.0284, 0.0284]
bse_pet0 = [0.0670, 0.0506]
bse_pet1 = [0.0234, 0.0334] #year
bse_pet01 = [0.0651, 0.0536] #firm and year
bse_0 = sw.se_cov(covg)
bse_1 = sw.se_cov(covt)
bse_01 = sw.se_cov(cov01)
#print res.HC0_se, bse_petw - res.HC0_se
#print bse_0, bse_0 - bse_pet0
#print bse_1, bse_1 - bse_pet1
#print bse_01, bse_01 - bse_pet01
assert_almost_equal(bse_petw, res.HC0_se, decimal=4)
assert_almost_equal(bse_0, bse_pet0, decimal=4)
assert_almost_equal(bse_1, bse_pet1, decimal=4)
assert_almost_equal(bse_01, bse_pet01, decimal=4)
import scikits.statsmodels.api as sm
import scikits.statsmodels.sandbox.panel.sandwich_covariance as sw
import scikits.statsmodels.sandbox.panel.sandwich_covariance_generic as swg
#requires Petersen's test_data
#http://www.kellogg.northwestern.edu/faculty/petersen/htm/papers/se/test_data.txt
pet = np.genfromtxt("test_data.txt")
endog = pet[:,-1]
group = pet[:,0].astype(int)
time = pet[:,1].astype(int)
exog = sm.add_constant(pet[:,2], prepend=True)
res = sm.OLS(endog, exog).fit()
cov01, covg, covt = sw.cov_cluster_2groups(res, group, group2=time)
#Reference number from Petersen
#http://www.kellogg.northwestern.edu/faculty/petersen/htm/papers/se/test_data.htm
bse_petw = [0.0284, 0.0284]
bse_pet0 = [0.0670, 0.0506]
bse_pet1 = [0.0234, 0.0334] #year
bse_pet01 = [0.0651, 0.0536] #firm and year
bse_0 = sw.se_cov(covg)
bse_1 = sw.se_cov(covt)
bse_01 = sw.se_cov(cov01)
print res.HC0_se, bse_petw - res.HC0_se
print bse_0, bse_0 - bse_pet0
print bse_1, bse_1 - bse_pet1
print bse_01, bse_01 - bse_pet01