def _partial_regression(endog, exog_i, exog_others):
"""Partial regression.
regress endog on exog_i conditional on exog_others
uses OLS
Parameters
----------
endog : array_like
exog : array_like
exog_others : array_like
Returns
-------
res1c : OLS results instance
(res1a, res1b) : tuple of OLS results instances
results from regression of endog on exog_others and of exog_i on
exog_others
"""
#FIXME: This function doesn't appear to be used.
res1a = OLS(endog, exog_others).fit()
res1b = OLS(exog_i, exog_others).fit()
res1c = OLS(res1a.resid, res1b.resid).fit()
return res1c, (res1a, res1b)
def reset_ramsey(res, degree=5):
'''Ramsey's RESET specification test for linear models
This is a general specification test, for additional non-linear effects
in a model.
Notes
-----
The test fits an auxiliary OLS regression where the design matrix, exog,
is augmented by powers 2 to degree of the fitted values. Then it performs
an F-test whether these additional terms are significant.
If the p-value of the f-test is below a threshold, e.g. 0.1, then this
indicates that there might be additional non-linear effects in the model
and that the linear model is mis-specified.
References
----------
http://en.wikipedia.org/wiki/Ramsey_RESET_test
'''
order = degree + 1
k_vars = res.model.exog.shape[1]
#vander without constant and x:
y_fitted_vander = np.vander(res.fittedvalues,
order)[:, :-2] #drop constant
exog = np.column_stack((res.model.exog, y_fitted_vander))
res_aux = OLS(res.model.endog, exog).fit()
#r_matrix = np.eye(degree, exog.shape[1], k_vars)
r_matrix = np.eye(degree - 1, exog.shape[1], k_vars)
#df1 = degree - 1
#df2 = exog.shape[0] - degree - res.df_model (without constant)
return res_aux.f_test(r_matrix) #, r_matrix, res_aux
def reset_ramsey(res, degree=5):
'''Ramsey's RESET specification test for linear models
This is a general specification test, for additional non-linear effects
in a model.
Notes
-----
The test fits an auxiliary OLS regression where the design matrix, exog,
is augmented by powers 2 to degree of the fitted values. Then it performs
an F-test whether these additional terms are significant.
If the p-value of the f-test is below a threshold, e.g. 0.1, then this
indicates that there might be additional non-linear effects in the model
and that the linear model is mis-specified.
References
----------
http://en.wikipedia.org/wiki/Ramsey_RESET_test
'''
order = degree + 1
k_vars = res.model.exog.shape[1]
#vander without constant and x:
y_fitted_vander = np.vander(res.fittedvalues, order)[:, :-2] #drop constant
exog = np.column_stack((res.model.exog, y_fitted_vander))
res_aux = OLS(res.model.endog, exog).fit()
#r_matrix = np.eye(degree, exog.shape[1], k_vars)
r_matrix = np.eye(degree-1, exog.shape[1], k_vars)
#df1 = degree - 1
#df2 = exog.shape[0] - degree - res.df_model (without constant)
return res_aux.f_test(r_matrix) #, r_matrix, res_aux
def notyet_atst():
d = macrodata.load().data
realinv = d['realinv']
realgdp = d['realgdp']
realint = d['realint']
endog = realinv
exog = add_constant(np.c_[realgdp, realint],prepend=True)
res_ols1 = OLS(endog, exog).fit()
#growth rates
gs_l_realinv = 400 * np.diff(np.log(d['realinv']))
gs_l_realgdp = 400 * np.diff(np.log(d['realgdp']))
lint = d['realint'][:-1]
tbilrate = d['tbilrate'][:-1]
endogg = gs_l_realinv
exogg = add_constant(np.c_[gs_l_realgdp, lint], prepend=True)
exogg2 = add_constant(np.c_[gs_l_realgdp, tbilrate], prepend=True)
res_ols = OLS(endogg, exogg).fit()
res_ols2 = OLS(endogg, exogg2).fit()
#the following were done accidentally with res_ols1 in R,
#with original Greene data
params = np.array([-272.3986041341653, 0.1779455206941112,
0.2149432424658157])
cov_hac_4 = np.array([1321.569466333051, -0.2318836566017612,
37.01280466875694, -0.2318836566017614, 4.602339488102263e-05,
-0.0104687835998635, 37.012804668757, -0.0104687835998635,
21.16037144168061]).reshape(3,3, order='F')
cov_hac_10 = np.array([2027.356101193361, -0.3507514463299015,
54.81079621448568, -0.350751446329901, 6.953380432635583e-05,
-0.01268990195095196, 54.81079621448564, -0.01268990195095195,
22.92512402151113]).reshape(3,3, order='F')
#goldfeld-quandt
het_gq_greater = dict(statistic=13.20512768685082, df1=99, df2=98,
pvalue=1.246141976112324e-30, distr='f')
het_gq_less = dict(statistic=13.20512768685082, df1=99, df2=98, pvalue=1.)
het_gq_2sided = dict(statistic=13.20512768685082, df1=99, df2=98,
pvalue=1.246141976112324e-30, distr='f')
#goldfeld-quandt, fraction = 0.5
het_gq_greater_2 = dict(statistic=87.1328934692124, df1=48, df2=47,
pvalue=2.154956842194898e-33, distr='f')
gq = smsdia.het_goldfeldquandt(endog, exog, split=0.5)
compare_t_est(gq, het_gq_greater, decimal=(13, 14))
assert_equal(gq[-1], 'increasing')
harvey_collier = dict(stat=2.28042114041313, df=199,
pvalue=0.02364236161988260, distr='t')
#hc = harvtest(fm, order.by=ggdp , data = list())
harvey_collier_2 = dict(stat=0.7516918462158783, df=199,
pvalue=0.4531244858006127, distr='t')
def setupClass(cls):
data = longley.load()
data.exog = add_constant(data.exog)
res1 = OLS(data.endog, data.exog).fit()
R = np.array([[0, 1, 1, 0, 0, 0, 0], [0, 1, 0, 1, 0, 0, 0],
[0, 1, 0, 0, 0, 0, 0], [0, 0, 0, 0, 1, 0, 0],
[0, 0, 0, 0, 0, 1, 0]])
q = np.array([0, 0, 0, 1, 0])
cls.Ftest1 = res1.f_test(R, q)
def coint(y1, y2, regression="c"):
"""
This is a simple cointegration test. Uses unit-root test on residuals to
test for cointegrated relationship
See Hamilton (1994) 19.2
Parameters
----------
y1 : array_like, 1d
first element in cointegrating vector
y2 : array_like
remaining elements in cointegrating vector
c : str {'c'}
Included in regression
* 'c' : Constant
Returns
-------
coint_t : float
t-statistic of unit-root test on residuals
pvalue : float
MacKinnon's approximate p-value based on MacKinnon (1994)
crit_value : dict
Critical values for the test statistic at the 1 %, 5 %, and 10 % levels.
Notes
-----
The Null hypothesis is that there is no cointegration, the alternative
hypothesis is that there is cointegrating relationship. If the pvalue is
small, below a critical size, then we can reject the hypothesis that there
is no cointegrating relationship.
P-values are obtained through regression surface approximation from
MacKinnon 1994.
References
----------
MacKinnon, J.G. 1994. "Approximate asymptotic distribution functions for
unit-root and cointegration tests. `Journal of Business and Economic
Statistics` 12, 167-76.
"""
regression = regression.lower()
if regression not in ['c', 'nc', 'ct', 'ctt']:
raise ValueError("regression option %s not understood") % regression
y1 = np.asarray(y1)
y2 = np.asarray(y2)
if regression == 'c':
y2 = add_constant(y2)
st1_resid = OLS(y1, y2).fit().resid #stage one residuals
lgresid_cons = add_constant(st1_resid[0:-1])
uroot_reg = OLS(st1_resid[1:], lgresid_cons).fit()
coint_t = (uroot_reg.params[0] - 1) / uroot_reg.bse[0]
pvalue = mackinnonp(coint_t, regression="c", N=2, lags=None)
crit_value = mackinnoncrit(N=1, regression="c", nobs=len(y1))
return coint_t, pvalue, crit_value
def setupClass(cls):
data = longley.load()
data.exog = add_constant(data.exog)
res1 = OLS(data.endog, data.exog).fit()
R = np.array([[0,1,1,0,0,0,0],
[0,1,0,1,0,0,0],
[0,1,0,0,0,0,0],
[0,0,0,0,1,0,0],
[0,0,0,0,0,1,0]])
q = np.array([0,0,0,1,0])
cls.Ftest1 = res1.f_test(R,q)
def setupClass(cls):
from results.results_regression import Longley
data = longley.load()
data.exog = add_constant(data.exog)
res1 = OLS(data.endog, data.exog).fit()
res2 = Longley()
res2.wresid = res1.wresid # workaround hack
cls.res1 = res1
cls.res2 = res2
res_qr = OLS(data.endog, data.exog).fit(method="qr")
cls.res_qr = res_qr
def qqline(ax, line, x=None, y=None, dist=None, fmt='r-'):
"""
Plot a reference line for a qqplot.
Parameters
----------
ax : matplotlib axes instance
The axes on which to plot the line
line : str {'45','r','s','q'}
Options for the reference line to which the data is compared.:
- '45' - 45-degree line
- 's' - standardized line, the expected order statistics are scaled by the standard deviation of the given sample and have the mean added
to them
- 'r' - A regression line is fit
- 'q' - A line is fit through the quartiles.
- None - By default no reference line is added to the plot.
x : array
X data for plot. Not needed if line is '45'.
y : array
Y data for plot. Not needed if line is '45'.
dist : scipy.stats.distribution
A scipy.stats distribution, needed if line is 'q'.
Notes
-----
There is no return value. The line is plotted on the given `ax`.
"""
if line == '45':
end_pts = zip(ax.get_xlim(), ax.get_ylim())
end_pts[0] = max(end_pts[0])
end_pts[1] = min(end_pts[1])
ax.plot(end_pts, end_pts, fmt)
return # does this have any side effects?
if x is None and y is None:
raise ValueError("If line is not 45, x and y cannot be None.")
elif line == 'r':
# could use ax.lines[0].get_xdata(), get_ydata(),
# but don't know axes are 'clean'
y = OLS(y, add_constant(x)).fit().fittedvalues
ax.plot(x, y, fmt)
elif line == 's':
m, b = y.std(), y.mean()
ref_line = x * m + b
ax.plot(x, ref_line, fmt)
elif line == 'q':
q25 = stats.scoreatpercentile(y, 25)
q75 = stats.scoreatpercentile(y, 75)
theoretical_quartiles = dist.ppf([.25, .75])
m = (q75 - q25) / np.diff(theoretical_quartiles)
b = q25 - m * theoretical_quartiles[0]
ax.plot(x, m * x + b, fmt)
def qqline(ax, line, x=None, y=None, dist=None, fmt='r-'):
"""
Plot a reference line for a qqplot.
Parameters
----------
ax : matplotlib axes instance
The axes on which to plot the line
line : str {'45','r','s','q'}
Options for the reference line to which the data is compared.:
- '45' - 45-degree line
- 's' - standardized line, the expected order statistics are scaled by the standard deviation of the given sample and have the mean added
to them
- 'r' - A regression line is fit
- 'q' - A line is fit through the quartiles.
- None - By default no reference line is added to the plot.
x : array
X data for plot. Not needed if line is '45'.
y : array
Y data for plot. Not needed if line is '45'.
dist : scipy.stats.distribution
A scipy.stats distribution, needed if line is 'q'.
Notes
-----
There is no return value. The line is plotted on the given `ax`.
"""
if line == '45':
end_pts = zip(ax.get_xlim(), ax.get_ylim())
end_pts[0] = max(end_pts[0])
end_pts[1] = min(end_pts[1])
ax.plot(end_pts, end_pts, fmt)
return # does this have any side effects?
if x is None and y is None:
raise ValueError("If line is not 45, x and y cannot be None.")
elif line == 'r':
# could use ax.lines[0].get_xdata(), get_ydata(),
# but don't know axes are 'clean'
y = OLS(y, add_constant(x)).fit().fittedvalues
ax.plot(x,y,fmt)
elif line == 's':
m,b = y.std(), y.mean()
ref_line = x*m + b
ax.plot(x, ref_line, fmt)
elif line == 'q':
q25 = stats.scoreatpercentile(y, 25)
q75 = stats.scoreatpercentile(y, 75)
theoretical_quartiles = dist.ppf([.25,.75])
m = (q75 - q25) / np.diff(theoretical_quartiles)
b = q25 - m*theoretical_quartiles[0]
ax.plot(x, m*x + b, fmt)
def setupClass(cls):
# if skipR:
# raise SkipTest, "Rpy not installed"
# try:
# r.library('car')
# except RPyRException:
# raise SkipTest, "car library not installed for R"
R = np.zeros(7)
R[4:6] = [1, -1]
# self.R = R
data = longley.load()
data.exog = add_constant(data.exog)
res1 = OLS(data.endog, data.exog).fit()
cls.Ttest1 = res1.t_test(R)
def setupClass(cls):
# if skipR:
# raise SkipTest, "Rpy not installed"
# try:
# r.library('car')
# except RPyRException:
# raise SkipTest, "car library not installed for R"
R = np.zeros(7)
R[4:6] = [1,-1]
# self.R = R
data = longley.load()
data.exog = add_constant(data.exog)
res1 = OLS(data.endog, data.exog).fit()
cls.Ttest1 = res1.t_test(R)
def __init__(self):
super(self.__class__, self).__init__() #initialize DGP
nobs = self.nobs
y_true, x, exog = self.y_true, self.x, self.exog
np.random.seed(8765993)
sigma_noise = 0.1
y = y_true + sigma_noise * np.random.randn(nobs)
m = AdditiveModel(x)
m.fit(y)
res_gam = m.results #TODO: currently attached to class
res_ols = OLS(y, exog).fit()
#Note: there still are some naming inconsistencies
self.res1 = res1 = Dummy() #for gam model
#res2 = Dummy() #for benchmark
self.res2 = res2 = res_ols #reuse existing ols results, will add additional
res1.y_pred = res_gam.predict(x)
res2.y_pred = res_ols.model.predict(res_ols.params, exog)
res1.y_predshort = res_gam.predict(x[:10])
slopes = [i for ss in m.smoothers for i in ss.params[1:]]
const = res_gam.alpha + sum([ss.params[1] for ss in m.smoothers])
#print const, slopes
res1.params = np.array([const] + slopes)
def fitbygroups(self):
'''Fit OLS regression for each group separately.
Returns
-------
results are attached
olsbygroup : dictionary of result instance
the returned regression results for each group
sigmabygroup : array (ngroups,) (this should be called sigma2group ??? check)
mse_resid for each group
weights : array (nobs,)
standard deviation of group extended to the original observations. This can
be used as weights in WLS for group-wise heteroscedasticity.
'''
olsbygroup = {}
sigmabygroup = []
for gi, group in enumerate(
self.unique): #np.arange(len(self.unique))):
groupmask = self.groupsint == gi #group index
res = OLS(self.endog[groupmask], self.exog[groupmask]).fit()
olsbygroup[group] = res
sigmabygroup.append(res.mse_resid)
self.olsbygroup = olsbygroup
self.sigmabygroup = np.array(sigmabygroup)
self.weights = np.sqrt(
self.sigmabygroup[self.groupsint]) #TODO:chk sqrt
def setupClass(cls):
data = longley.load()
data.exog = add_constant(data.exog)
ols_res = OLS(data.endog, data.exog).fit()
gls_res = GLS(data.endog, data.exog).fit()
cls.res1 = gls_res
cls.res2 = ols_res
def pacf_ols(x, nlags=40):
'''Calculate partial autocorrelations
Parameters
----------
x : 1d array
observations of time series for which pacf is calculated
nlags : int
Number of lags for which pacf is returned. Lag 0 is not returned.
Returns
-------
pacf : 1d array
partial autocorrelations, maxlag+1 elements
Notes
-----
This solves a separate OLS estimation for each desired lag.
'''
#TODO: add warnings for Yule-Walker
#NOTE: demeaning and not using a constant gave incorrect answers?
#JP: demeaning should have a better estimate of the constant
#maybe we can compare small sample properties with a MonteCarlo
xlags, x0 = lagmat(x, nlags, original='sep')
#xlags = sm.add_constant(lagmat(x, nlags), prepend=True)
xlags = add_constant(xlags, prepend=True)
pacf = [1.]
for k in range(1, nlags + 1):
res = OLS(x0[k:], xlags[k:, :k + 1]).fit()
#np.take(xlags[k:], range(1,k+1)+[-1],
pacf.append(res.params[-1])
return np.array(pacf)
def setupClass(cls):
np.random.seed(54321)
cls.endog_n_ = np.random.uniform(0, 20, size=30)
cls.endog_n_one = cls.endog_n_[:, None]
cls.exog_n_ = np.random.uniform(0, 20, size=30)
cls.exog_n_one = cls.exog_n_[:, None]
cls.degen_exog = cls.exog_n_one[:-1]
cls.mod1 = OLS(cls.endog_n_one, cls.exog_n_one)
cls.mod1.df_model += 1
#cls.mod1.df_resid -= 1
cls.res1 = cls.mod1.fit()
# Note that these are created for every subclass..
# A little extra overhead probably
cls.mod2 = OLS(cls.endog_n_one, cls.exog_n_one)
cls.mod2.df_model += 1
cls.res2 = cls.mod2.fit()
def spec_hausman(self, dof=None):
'''Hausman's specification test
See Also
--------
spec_hausman : generic function for Hausman's specification test
'''
#use normalized cov_params for OLS
resols = OLS(endog, exog).fit()
normalized_cov_params_ols = resols.model.normalized_cov_params
se2 = resols.mse_resid
params_diff = self._results.params - resols.params
cov_diff = np.linalg.pinv(self.xhatprod) - normalized_cov_params_ols
#TODO: the following is very inefficient, solves problem (svd) twice
#use linalg.lstsq or svd directly
#cov_diff will very often be in-definite (singular)
if not dof:
dof = tools.rank(cov_diff)
cov_diffpinv = np.linalg.pinv(cov_diff)
H = np.dot(params_diff, np.dot(cov_diffpinv, params_diff))/se2
pval = stats.chi2.sf(H, dof)
return H, pval, dof
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)
def test_hac_simple():
from gwstatsmodels.datasets import macrodata
d2 = macrodata.load().data
g_gdp = 400 * np.diff(np.log(d2['realgdp']))
g_inv = 400 * np.diff(np.log(d2['realinv']))
exogg = add_constant(np.c_[g_gdp, d2['realint'][:-1]], prepend=True)
res_olsg = OLS(g_inv, exogg).fit()
#> NeweyWest(fm, lag = 4, prewhite = FALSE, sandwich = TRUE, verbose=TRUE, adjust=TRUE)
#Lag truncation parameter chosen: 4
# (Intercept) ggdp lint
cov1_r = [
[1.40643899878678802, -0.3180328707083329709, -0.060621111216488610],
[-0.31803287070833292, 0.1097308348999818661, 0.000395311760301478],
[-0.06062111121648865, 0.0003953117603014895, 0.087511528912470993]
]
#> NeweyWest(fm, lag = 4, prewhite = FALSE, sandwich = TRUE, verbose=TRUE, adjust=FALSE)
#Lag truncation parameter chosen: 4
# (Intercept) ggdp lint
cov2_r = [
[1.3855512908840137, -0.313309610252268500, -0.059720797683570477],
[-0.3133096102522685, 0.108101169035130618, 0.000389440793564339],
[-0.0597207976835705, 0.000389440793564336, 0.086211852740503622]
]
cov1, se1 = sw.cov_hac_simple(res_olsg, nlags=4, use_correction=True)
cov2, se2 = sw.cov_hac_simple(res_olsg, nlags=4, use_correction=False)
assert_almost_equal(cov1, cov1_r, decimal=14)
assert_almost_equal(cov2, cov2_r, decimal=14)
def iterative_fit(self, maxiter=3):
"""
Perform an iterative two-step procedure to estimate a WLS model.
The model is assumed to have heteroscedastic errors.
The variance is estimated by OLS regression of the link transformed
squared residuals on Z, i.e.::
link(sigma_i) = x_i*gamma.
Parameters
----------
maxiter : integer, optional
the number of iterations
Notes
-----
maxiter=1: returns the estimated based on given weights
maxiter=2: performs a second estimation with the updated weights,
this is 2-step estimation
maxiter>2: iteratively estimate and update the weights
TODO: possible extension stop iteration if change in parameter
estimates is smaller than x_tol
Repeated calls to fit_iterative, will do one redundant pinv_wexog
calculation. Calling fit_iterative(maxiter) ones does not do any
redundant recalculations (whitening or calculating pinv_wexog).
"""
import collections
self.history = collections.defaultdict(list) #not really necessary
res_resid = None #if maxiter < 2 no updating
for i in range(maxiter):
#pinv_wexog is cached
if hasattr(self, 'pinv_wexog'):
del self.pinv_wexog
#self.initialize()
#print 'wls self',
results = self.fit()
self.history['self_params'].append(results.params)
if not i == maxiter - 1: #skip for last iteration, could break instead
#print 'ols',
self.results_old = results #for debugging
#estimate heteroscedasticity
res_resid = OLS(self.link(results.resid**2),
self.exog_var).fit()
self.history['ols_params'].append(res_resid.params)
#update weights
self.weights = 1. / self.linkinv(res_resid.fittedvalues)
self.weights /= self.weights.max() #not required
self.weights[self.weights < 1e-14] = 1e-14 #clip
#print 'in iter', i, self.weights.var() #debug, do weights change
self.initialize()
#note results is the wrapper, results._results is the results instance
results._results.results_residual_regression = res_resid
return results
def fit(self):
res_pooled = self.fit_ols() #get starting estimate
sigma_i = self.get_within_cov(res_pooled.resid)
self.cholsigmainv_i = np.linalg.cholesky(np.linalg.pinv(sigma_i)).T
wendog = self.whiten_groups(self.endog, self.cholsigmainv_i)
wexog = self.whiten_groups(self.exog, self.cholsigmainv_i)
print wendog.shape, wexog.shape
self.res1 = OLS(wendog, wexog).fit()
return self.res1
def test_recursive_residuals(self):
reccumres_standardize = np.array([-2.151, -3.748, -3.114, -3.096,
-1.865, -2.230, -1.194, -3.500, -3.638, -4.447, -4.602, -4.631, -3.999,
-4.830, -5.429, -5.435, -6.554, -8.093, -8.567, -7.532, -7.079, -8.468,
-9.320, -12.256, -11.932, -11.454, -11.690, -11.318, -12.665, -12.842,
-11.693, -10.803, -12.113, -12.109, -13.002, -11.897, -10.787, -10.159,
-9.038, -9.007, -8.634, -7.552, -7.153, -6.447, -5.183, -3.794, -3.511,
-3.979, -3.236, -3.793, -3.699, -5.056, -5.724, -4.888, -4.309, -3.688,
-3.918, -3.735, -3.452, -2.086, -6.520, -7.959, -6.760, -6.855, -6.032,
-4.405, -4.123, -4.075, -3.235, -3.115, -3.131, -2.986, -1.813, -4.824,
-4.424, -4.796, -4.000, -3.390, -4.485, -4.669, -4.560, -3.834, -5.507,
-3.792, -2.427, -1.756, -0.354, 1.150, 0.586, 0.643, 1.773, -0.830,
-0.388, 0.517, 0.819, 2.240, 3.791, 3.187, 3.409, 2.431, 0.668, 0.957,
-0.928, 0.327, -0.285, -0.625, -2.316, -1.986, -0.744, -1.396, -1.728,
-0.646, -2.602, -2.741, -2.289, -2.897, -1.934, -2.532, -3.175, -2.806,
-3.099, -2.658, -2.487, -2.515, -2.224, -2.416, -1.141, 0.650, -0.947,
0.725, 0.439, 0.885, 2.419, 2.642, 2.745, 3.506, 4.491, 5.377, 4.624,
5.523, 6.488, 6.097, 5.390, 6.299, 6.656, 6.735, 8.151, 7.260, 7.846,
8.771, 8.400, 8.717, 9.916, 9.008, 8.910, 8.294, 8.982, 8.540, 8.395,
7.782, 7.794, 8.142, 8.362, 8.400, 7.850, 7.643, 8.228, 6.408, 7.218,
7.699, 7.895, 8.725, 8.938, 8.781, 8.350, 9.136, 9.056, 10.365, 10.495,
10.704, 10.784, 10.275, 10.389, 11.586, 11.033, 11.335, 11.661, 10.522,
10.392, 10.521, 10.126, 9.428, 9.734, 8.954, 9.949, 10.595, 8.016,
6.636, 6.975])
rr = smsdia.recursive_olsresiduals(self.res, skip=3, alpha=0.95)
assert_equal(np.round(rr[5][1:], 3), reccumres_standardize) #extra zero in front
#assert_equal(np.round(rr[3][4:], 3), np.diff(reccumres_standardize))
assert_almost_equal(rr[3][4:], np.diff(reccumres_standardize),3)
assert_almost_equal(rr[4][3:].std(ddof=1), 10.7242, decimal=4)
#regression number, visually checked with graph from gretl
ub0 = np.array([ 13.37318571, 13.50758959, 13.64199346, 13.77639734,
13.91080121])
ub1 = np.array([ 39.44753774, 39.58194162, 39.7163455 , 39.85074937,
39.98515325])
lb, ub = rr[6]
assert_almost_equal(ub[:5], ub0, decimal=7)
assert_almost_equal(lb[:5], -ub0, decimal=7)
assert_almost_equal(ub[-5:], ub1, decimal=7)
assert_almost_equal(lb[-5:], -ub1, decimal=7)
#test a few values with explicit OLS
endog = self.res.model.endog
exog = self.res.model.exog
params = []
ypred = []
for i in range(3,10):
resi = OLS(endog[:i], exog[:i]).fit()
ypred.append(resi.model.predict(resi.params, exog[i]))
params.append(resi.params)
assert_almost_equal(rr[2][3:10], ypred, decimal=12)
assert_almost_equal(rr[0][3:10], endog[3:10] - ypred, decimal=12)
assert_almost_equal(rr[1][2:9], params, decimal=12)
def fitpooled(self):
'''fit the pooled model, which assumes there are no differences across groups
'''
if self.het:
if not hasattr(self, 'weights'):
self.fitbygroups()
weights = self.weights
res = WLS(self.endog, self.exog, weights=weights).fit()
else:
res = OLS(self.endog, self.exog).fit()
self.lspooled = res
def __init__(self):
super(self.__class__, self).__init__() #initialize DGP
y, x, exog = self.y, self.x, self.exog
#use order = 2 in regression
pmod = smoothers.PolySmoother(2, x)
pmod.fit(y) #no return
self.res_ps = pmod
self.res2 = OLS(y, exog[:, :2 + 1]).fit()
def plot_partregress_ax(endog, exog_i, exog_others, varname='',
title_fontsize=None, ax=None):
"""Plot partial regression for a single regressor.
Parameters
----------
endog : ndarray
endogenous or response variable
exog_i : ndarray
exogenous, explanatory variable
exog_others : ndarray
other exogenous, explanatory variables, the effect of these variables
will be removed by OLS regression
varname : str
name of the variable used in the title
ax : Matplotlib AxesSubplot instance, optional
If given, this subplot is used to plot in instead of a new figure being
created.
Returns
-------
fig : Matplotlib figure instance
If `ax` is None, the created figure. Otherwise the figure to which
`ax` is connected.
See Also
--------
plot_partregress : Plot partial regression for a set of regressors.
"""
fig, ax = utils.create_mpl_ax(ax)
res1a = OLS(endog, exog_others).fit()
res1b = OLS(exog_i, exog_others).fit()
ax.plot(res1b.resid, res1a.resid, 'o')
res1c = OLS(res1a.resid, res1b.resid).fit()
ax.plot(res1b.resid, res1c.fittedvalues, '-', color='k')
ax.set_title('Partial Regression plot %s' % varname,
fontsize=title_fontsize)# + namestr)
return fig
def fit(self):
alpha0 = 0.1 #startvalue
func = self.fit_conditional
fitres = optimize.fmin(func, alpha0)
# fit_conditional only returns ssr for now
alpha = fitres[0]
y = self.ar1filter(self.endog, alpha)
x = self.ar1filter(self.exog, alpha)
reso = OLS(y, x).fit()
return fitres, reso
def __init__(self):
super(self.__class__, self).__init__() #initialize DGP
y, x, exog = self.y, self.x, self.exog
#use order = 3 in regression
pmod = smoothers.PolySmoother(3, x)
#pmod.fit(y) #no return
pmod.smooth(y) #no return, use alias for fit
self.res_ps = pmod
self.res2 = OLS(y, exog[:, :3 + 1]).fit()
def setupClass(cls):
from results.results_regression import LongleyGls
data = longley.load()
exog = add_constant(np.column_stack(\
(data.exog[:,1],data.exog[:,4])))
tmp_results = OLS(data.endog, exog).fit()
rho = np.corrcoef(tmp_results.resid[1:],
tmp_results.resid[:-1])[0][1] # by assumption
order = toeplitz(np.arange(16))
sigma = rho**order
GLS_results = GLS(data.endog, exog, sigma=sigma).fit()
cls.res1 = GLS_results
cls.res2 = LongleyGls()
def _ols_xnoti(self, drop_idx, endog_idx='endog', store=True):
'''regression results from LOVO auxiliary regression with cache
The result instances are stored, which could use a large amount of
memory if the datasets are large. There are too many combinations to
store them all, except for small problems.
Parameters
----------
drop_idx : int
index of exog that is dropped from the regression
endog_idx : 'endog' or int
If 'endog', then the endogenous variable of the result instance
is regressed on the exogenous variables, excluding the one at
drop_idx. If endog_idx is an integer, then the exog with that
index is regressed with OLS on all other exogenous variables.
(The latter is the auxiliary regression for the variance inflation
factor.)
this needs more thought, memory versus speed
not yet used in any other parts, not sufficiently tested
'''
#reverse the structure, access store, if fail calculate ?
#this creates keys in store even if store = false ! bug
if endog_idx == 'endog':
stored = self.aux_regression_endog
if hasattr(stored, drop_idx):
return stored[drop_idx]
x_i = self.results.model.endog
else:
#nested dictionary
try:
self.aux_regression_exog[endog_idx][drop_idx]
except KeyError:
pass
stored = self.aux_regression_exog[endog_idx]
stored = {}
x_i = self.exog[:, endog_idx]
mask = np.arange(k_vars) != drop_idx
x_noti = self.exog[:, mask]
res = OLS(x_i, x_noti).fit()
if store:
stored[drop_idx] = res
return res
def __init__(self):
d = macrodata.load().data
#growth rates
gs_l_realinv = 400 * np.diff(np.log(d['realinv']))
gs_l_realgdp = 400 * np.diff(np.log(d['realgdp']))
lint = d['realint'][:-1]
tbilrate = d['tbilrate'][:-1]
endogg = gs_l_realinv
exogg = add_constant(np.c_[gs_l_realgdp, lint], prepend=True)
exogg2 = add_constant(np.c_[gs_l_realgdp, tbilrate], prepend=True)
exogg3 = add_constant(np.c_[gs_l_realgdp], prepend=True)
res_ols = OLS(endogg, exogg).fit()
res_ols2 = OLS(endogg, exogg2).fit()
res_ols3 = OLS(endogg, exogg3).fit()
self.res = res_ols
self.res2 = res_ols2
self.res3 = res_ols3
self.endog = self.res.model.endog
self.exog = self.res.model.exog
def fit(self, lambd=1.):
#maybe iterate
#preliminary estimate
res_gls = GLS(self.endog, self.exog, sigma=self.sigma).fit()
res_resid = OLS(res_gls.resid**2, self.exog_var).fit()
#or log-link
#res_resid = OLS(np.log(res_gls.resid**2), self.exog_var).fit()
#here I could use whiten and current instance instead of delegating
#but this is easier
#see pattern of GLSAR, calls self.initialize and self.fit
res_wls = WLS(self.endog,
self.exog,
weights=1. / res_resid.fittedvalues).fit()
res_wls._results.results_residual_regression = res_resid
return res_wls
def variance_inflation_factor(exog, exog_idx):
'''variance inflation factor, VIF, for one exogenous variable
The variance inflation factor is a measure for the increase of the
variance of the parameter estimates if an additional variable, given by
exog_idx is added to the linear regression. It is a measure for
multicollinearity of the design matrix, exog.
One recommendation is that if VIF is greater than 5, then the explanatory
variable given by exog_idx is highly collinear with the other explanatory
variables, and the parameter estimates will have large standard errors
because of this.
Parameters
----------
exog : ndarray, (nobs, k_vars)
design matrix with all explanatory variables, as for example used in
regression
exog_idx : int
index of the exogenous variable in the columns of exog
Returns
-------
vif : float
variance inflation factor
Notes
-----
This function does not save the auxiliary regression.
See Also
--------
xxx : class for regression diagnostics TODO: doesn't exist yet
References
----------
http://en.wikipedia.org/wiki/Variance_inflation_factor
'''
k_vars = exog.shape[1]
x_i = exog[:, exog_idx]
mask = np.arange(k_vars) != exog_idx
x_noti = exog[:, mask]
r_squared_i = OLS(x_i, x_noti).fit().rsquared
vif = 1. / (1. - r_squared_i)
return vif
#using GMM and IV2SLS classes
#----------------------------
mod = IVGMM(endog, exog, instrument, nmoms=instrument.shape[1])
res = mod.fit()
modgmmols = IVGMM(endog, exog, exog, nmoms=exog.shape[1])
resgmmols = modgmmols.fit()
#the next is the same as IV2SLS, (Z'Z)^{-1} as weighting matrix
modgmmiv = IVGMM(endog, exog, instrument, nmoms=instrument.shape[1]) #same as mod
resgmmiv = modgmmiv.fitgmm(np.ones(exog.shape[1], float),
weights=np.linalg.inv(np.dot(instrument.T, instrument)))
modls = IV2SLS(endog, exog, instrument)
resls = modls.fit()
modols = OLS(endog, exog)
resols = modols.fit()
print '\nIV case'
print 'params'
print 'IV2SLS', resls.params
print 'GMMIV ', resgmmiv # .params
print 'GMM ', res.params
print 'diff ', res.params - resls.params
print 'OLS ', resols.params
print 'GMMOLS', resgmmols.params
print '\nbse'
print 'IV2SLS', resls.bse
print 'GMM ', mod.bse #bse currently only attached to model not results
print 'diff ', mod.bse - resls.bse
def setupClass(cls):
data = longley.load()
data.exog = add_constant(data.exog)
res1 = OLS(data.endog, data.exog).fit()
R2 = [[0,1,-1,0,0,0,0],[0, 0, 0, 0, 1, -1, 0]]
cls.Ftest1 = res1.f_test(R2)
def test_all(self):
d = macrodata.load().data
#import datasetswsm.greene as g
#d = g.load('5-1')
#growth rates
gs_l_realinv = 400 * np.diff(np.log(d['realinv']))
gs_l_realgdp = 400 * np.diff(np.log(d['realgdp']))
#simple diff, not growthrate, I want heteroscedasticity later for testing
endogd = np.diff(d['realinv'])
exogd = add_constant(np.c_[np.diff(d['realgdp']), d['realint'][:-1]],
prepend=True)
endogg = gs_l_realinv
exogg = add_constant(np.c_[gs_l_realgdp, d['realint'][:-1]],
prepend=True)
res_ols = OLS(endogg, exogg).fit()
#print res_ols.params
mod_g1 = GLSAR(endogg, exogg, rho=-0.108136)
res_g1 = mod_g1.fit()
#print res_g1.params
mod_g2 = GLSAR(endogg, exogg, rho=-0.108136) #-0.1335859) from R
res_g2 = mod_g2.iterative_fit(maxiter=5)
#print res_g2.params
rho = -0.108136
# coefficient std. error t-ratio p-value 95% CONFIDENCE INTERVAL
partable = np.array([
[-9.50990, 0.990456, -9.602, 3.65e-018, -11.4631, -7.55670], # ***
[4.37040, 0.208146, 21.00, 2.93e-052, 3.95993, 4.78086], # ***
[-0.579253, 0.268009, -2.161, 0.0319, -1.10777, -0.0507346]
]) # **
#Statistics based on the rho-differenced data:
result_gretl_g1 = dict(endog_mean=("Mean dependent var", 3.113973),
endog_std=("S.D. dependent var", 18.67447),
ssr=("Sum squared resid", 22530.90),
mse_resid_sqrt=("S.E. of regression", 10.66735),
rsquared=("R-squared", 0.676973),
rsquared_adj=("Adjusted R-squared", 0.673710),
fvalue=("F(2, 198)", 221.0475),
f_pvalue=("P-value(F)", 3.56e-51),
resid_acf1=("rho", -0.003481),
dw=("Durbin-Watson", 1.993858))
#fstatistic, p-value, df1, df2
reset_2_3 = [5.219019, 0.00619, 2, 197, "f"]
reset_2 = [7.268492, 0.00762, 1, 198, "f"]
reset_3 = [5.248951, 0.023, 1, 198, "f"]
#LM-statistic, p-value, df
arch_4 = [7.30776, 0.120491, 4, "chi2"]
#multicollinearity
vif = [1.002, 1.002]
cond_1norm = 6862.0664
determinant = 1.0296049e+009
reciprocal_condition_number = 0.013819244
#Chi-square(2): test-statistic, pvalue, df
normality = [20.2792, 3.94837e-005, 2]
#tests
res = res_g1 #with rho from Gretl
#basic
assert_almost_equal(res.params, partable[:, 0], 4)
assert_almost_equal(res.bse, partable[:, 1], 6)
assert_almost_equal(res.tvalues, partable[:, 2], 2)
assert_almost_equal(res.ssr, result_gretl_g1['ssr'][1], decimal=2)
#assert_almost_equal(res.llf, result_gretl_g1['llf'][1], decimal=7) #not in gretl
#assert_almost_equal(res.rsquared, result_gretl_g1['rsquared'][1], decimal=7) #FAIL
#assert_almost_equal(res.rsquared_adj, result_gretl_g1['rsquared_adj'][1], decimal=7) #FAIL
assert_almost_equal(np.sqrt(res.mse_resid),
result_gretl_g1['mse_resid_sqrt'][1],
decimal=5)
assert_almost_equal(res.fvalue,
result_gretl_g1['fvalue'][1],
decimal=4)
assert_approx_equal(res.f_pvalue,
result_gretl_g1['f_pvalue'][1],
significant=2)
#assert_almost_equal(res.durbin_watson, result_gretl_g1['dw'][1], decimal=7) #TODO
#arch
#sm_arch = smsdia.acorr_lm(res.wresid**2, maxlag=4, autolag=None)
sm_arch = smsdia.het_arch(res.wresid, maxlag=4)
assert_almost_equal(sm_arch[0], arch_4[0], decimal=4)
assert_almost_equal(sm_arch[1], arch_4[1], decimal=6)
#tests
res = res_g2 #with estimated rho
#estimated lag coefficient
assert_almost_equal(res.model.rho, rho, decimal=3)
#basic
assert_almost_equal(res.params, partable[:, 0], 4)
assert_almost_equal(res.bse, partable[:, 1], 3)
assert_almost_equal(res.tvalues, partable[:, 2], 2)
assert_almost_equal(res.ssr, result_gretl_g1['ssr'][1], decimal=2)
#assert_almost_equal(res.llf, result_gretl_g1['llf'][1], decimal=7) #not in gretl
#assert_almost_equal(res.rsquared, result_gretl_g1['rsquared'][1], decimal=7) #FAIL
#assert_almost_equal(res.rsquared_adj, result_gretl_g1['rsquared_adj'][1], decimal=7) #FAIL
assert_almost_equal(np.sqrt(res.mse_resid),
result_gretl_g1['mse_resid_sqrt'][1],
decimal=5)
assert_almost_equal(res.fvalue,
result_gretl_g1['fvalue'][1],
decimal=0)
assert_almost_equal(res.f_pvalue,
result_gretl_g1['f_pvalue'][1],
decimal=6)
#assert_almost_equal(res.durbin_watson, result_gretl_g1['dw'][1], decimal=7) #TODO
c = oi.reset_ramsey(res, degree=2)
compare_ftest(c, reset_2, decimal=(2, 4))
c = oi.reset_ramsey(res, degree=3)
compare_ftest(c, reset_2_3, decimal=(2, 4))
#arch
#sm_arch = smsdia.acorr_lm(res.wresid**2, maxlag=4, autolag=None)
sm_arch = smsdia.het_arch(res.wresid, maxlag=4)
assert_almost_equal(sm_arch[0], arch_4[0], decimal=1)
assert_almost_equal(sm_arch[1], arch_4[1], decimal=2)
'''
Performing iterative calculation of rho...
ITER RHO ESS
1 -0.10734 22530.9
2 -0.10814 22530.9
Model 4: Cochrane-Orcutt, using observations 1959:3-2009:3 (T = 201)
Dependent variable: ds_l_realinv
rho = -0.108136
coefficient std. error t-ratio p-value
-------------------------------------------------------------
const -9.50990 0.990456 -9.602 3.65e-018 ***
ds_l_realgdp 4.37040 0.208146 21.00 2.93e-052 ***
realint_1 -0.579253 0.268009 -2.161 0.0319 **
Statistics based on the rho-differenced data:
Mean dependent var 3.113973 S.D. dependent var 18.67447
Sum squared resid 22530.90 S.E. of regression 10.66735
R-squared 0.676973 Adjusted R-squared 0.673710
F(2, 198) 221.0475 P-value(F) 3.56e-51
rho -0.003481 Durbin-Watson 1.993858
'''
'''
RESET test for specification (squares and cubes)
Test statistic: F = 5.219019,
with p-value = P(F(2,197) > 5.21902) = 0.00619
RESET test for specification (squares only)
Test statistic: F = 7.268492,
with p-value = P(F(1,198) > 7.26849) = 0.00762
RESET test for specification (cubes only)
Test statistic: F = 5.248951,
with p-value = P(F(1,198) > 5.24895) = 0.023:
'''
'''
Test for ARCH of order 4
coefficient std. error t-ratio p-value
--------------------------------------------------------
alpha(0) 97.0386 20.3234 4.775 3.56e-06 ***
alpha(1) 0.176114 0.0714698 2.464 0.0146 **
alpha(2) -0.0488339 0.0724981 -0.6736 0.5014
alpha(3) -0.0705413 0.0737058 -0.9571 0.3397
alpha(4) 0.0384531 0.0725763 0.5298 0.5968
Null hypothesis: no ARCH effect is present
Test statistic: LM = 7.30776
with p-value = P(Chi-square(4) > 7.30776) = 0.120491:
'''
'''
Variance Inflation Factors
Minimum possible value = 1.0
Values > 10.0 may indicate a collinearity problem
ds_l_realgdp 1.002
realint_1 1.002
VIF(j) = 1/(1 - R(j)^2), where R(j) is the multiple correlation coefficient
between variable j and the other independent variables
Properties of matrix X'X:
1-norm = 6862.0664
Determinant = 1.0296049e+009
Reciprocal condition number = 0.013819244
'''
'''
Test for ARCH of order 4 -
Null hypothesis: no ARCH effect is present
Test statistic: LM = 7.30776
with p-value = P(Chi-square(4) > 7.30776) = 0.120491
Test of common factor restriction -
Null hypothesis: restriction is acceptable
Test statistic: F(2, 195) = 0.426391
with p-value = P(F(2, 195) > 0.426391) = 0.653468
Test for normality of residual -
Null hypothesis: error is normally distributed
Test statistic: Chi-square(2) = 20.2792
with p-value = 3.94837e-005:
'''
#no idea what this is
'''
Augmented regression for common factor test
OLS, using observations 1959:3-2009:3 (T = 201)
Dependent variable: ds_l_realinv
coefficient std. error t-ratio p-value
---------------------------------------------------------------
const -10.9481 1.35807 -8.062 7.44e-014 ***
ds_l_realgdp 4.28893 0.229459 18.69 2.40e-045 ***
realint_1 -0.662644 0.334872 -1.979 0.0492 **
ds_l_realinv_1 -0.108892 0.0715042 -1.523 0.1294
ds_l_realgdp_1 0.660443 0.390372 1.692 0.0923 *
realint_2 0.0769695 0.341527 0.2254 0.8219
Sum of squared residuals = 22432.8
Test of common factor restriction
Test statistic: F(2, 195) = 0.426391, with p-value = 0.653468
'''
################ with OLS, HAC errors
#Model 5: OLS, using observations 1959:2-2009:3 (T = 202)
#Dependent variable: ds_l_realinv
#HAC standard errors, bandwidth 4 (Bartlett kernel)
#coefficient std. error t-ratio p-value 95% CONFIDENCE INTERVAL
#for confidence interval t(199, 0.025) = 1.972
partable = np.array([
[-9.48167, 1.17709, -8.055, 7.17e-014, -11.8029, -7.16049], # ***
[4.37422, 0.328787, 13.30, 2.62e-029, 3.72587, 5.02258], #***
[-0.613997, 0.293619, -2.091, 0.0378, -1.19300, -0.0349939]
]) # **
result_gretl_g1 = dict(endog_mean=("Mean dependent var", 3.257395),
endog_std=("S.D. dependent var", 18.73915),
ssr=("Sum squared resid", 22799.68),
mse_resid_sqrt=("S.E. of regression", 10.70380),
rsquared=("R-squared", 0.676978),
rsquared_adj=("Adjusted R-squared", 0.673731),
fvalue=("F(2, 199)", 90.79971),
f_pvalue=("P-value(F)", 9.53e-29),
llf=("Log-likelihood", -763.9752),
aic=("Akaike criterion", 1533.950),
bic=("Schwarz criterion", 1543.875),
hqic=("Hannan-Quinn", 1537.966),
resid_acf1=("rho", -0.107341),
dw=("Durbin-Watson", 2.213805))
linear_logs = [1.68351, 0.430953, 2, "chi2"]
#for logs: dropping 70 nan or incomplete observations, T=133
#(res_ols.model.exog <=0).any(1).sum() = 69 ?not 70
linear_squares = [7.52477, 0.0232283, 2, "chi2"]
#Autocorrelation, Breusch-Godfrey test for autocorrelation up to order 4
lm_acorr4 = [1.17928, 0.321197, 4, 195, "F"]
lm2_acorr4 = [4.771043, 0.312, 4, "chi2"]
acorr_ljungbox4 = [5.23587, 0.264, 4, "chi2"]
#break
cusum_Harvey_Collier = [0.494432, 0.621549, 198,
"t"] #stats.t.sf(0.494432, 198)*2
#see cusum results in files
break_qlr = [3.01985, 0.1, 3, 196,
"maxF"] #TODO check this, max at 2001:4
break_chow = [13.1897, 0.00424384, 3, "chi2"] # break at 1984:1
arch_4 = [3.43473, 0.487871, 4, "chi2"]
normality = [23.962, 0.00001, 2, "chi2"]
het_white = [33.503723, 0.000003, 5, "chi2"]
het_breush_pagan = [1.302014, 0.521520, 2,
"chi2"] #TODO: not available
het_breush_pagan_konker = [0.709924, 0.701200, 2, "chi2"]
reset_2_3 = [5.219019, 0.00619, 2, 197, "f"]
reset_2 = [7.268492, 0.00762, 1, 198, "f"]
reset_3 = [5.248951, 0.023, 1, 198, "f"] #not available
cond_1norm = 5984.0525
determinant = 7.1087467e+008
reciprocal_condition_number = 0.013826504
vif = [1.001, 1.001]
names = 'date residual leverage influence DFFITS'.split(
)
cur_dir = os.path.abspath(os.path.dirname(__file__))
fpath = os.path.join(cur_dir,
'results/leverage_influence_ols_nostars.txt')
lev = np.genfromtxt(fpath,
skip_header=3,
skip_footer=1,
converters={0: lambda s: s})
#either numpy 1.6 or python 3.2 changed behavior
if np.isnan(lev[-1]['f1']):
lev = np.genfromtxt(fpath,
skip_header=3,
skip_footer=2,
converters={0: lambda s: s})
lev.dtype.names = names
res = res_ols #for easier copying
cov_hac, bse_hac = sw.cov_hac_simple(res,
nlags=4,
use_correction=False)
assert_almost_equal(res.params, partable[:, 0], 5)
assert_almost_equal(bse_hac, partable[:, 1], 5)
#TODO
assert_almost_equal(res.ssr, result_gretl_g1['ssr'][1], decimal=2)
#assert_almost_equal(res.llf, result_gretl_g1['llf'][1], decimal=7) #not in gretl
assert_almost_equal(res.rsquared,
result_gretl_g1['rsquared'][1],
decimal=6) #FAIL
assert_almost_equal(res.rsquared_adj,
result_gretl_g1['rsquared_adj'][1],
decimal=6) #FAIL
assert_almost_equal(np.sqrt(res.mse_resid),
result_gretl_g1['mse_resid_sqrt'][1],
decimal=5)
#f-value is based on cov_hac I guess
#assert_almost_equal(res.fvalue, result_gretl_g1['fvalue'][1], decimal=0) #FAIL
#assert_approx_equal(res.f_pvalue, result_gretl_g1['f_pvalue'][1], significant=1) #FAIL
#assert_almost_equal(res.durbin_watson, result_gretl_g1['dw'][1], decimal=7) #TODO
c = oi.reset_ramsey(res, degree=2)
compare_ftest(c, reset_2, decimal=(6, 5))
c = oi.reset_ramsey(res, degree=3)
compare_ftest(c, reset_2_3, decimal=(6, 5))
linear_sq = smsdia.linear_lm(res.resid, res.model.exog)
assert_almost_equal(linear_sq[0], linear_squares[0], decimal=6)
assert_almost_equal(linear_sq[1], linear_squares[1], decimal=7)
hbpk = smsdia.het_breushpagan(res.resid, res.model.exog)
assert_almost_equal(hbpk[0], het_breush_pagan_konker[0], decimal=6)
assert_almost_equal(hbpk[1], het_breush_pagan_konker[1], decimal=6)
hw = smsdia.het_white(res.resid, res.model.exog)
assert_almost_equal(hw[:2], het_white[:2], 6)
#arch
#sm_arch = smsdia.acorr_lm(res.resid**2, maxlag=4, autolag=None)
sm_arch = smsdia.het_arch(res.resid, maxlag=4)
assert_almost_equal(sm_arch[0], arch_4[0], decimal=5)
assert_almost_equal(sm_arch[1], arch_4[1], decimal=6)
vif2 = [
oi.variance_inflation_factor(res.model.exog, k) for k in [1, 2]
]
infl = oi.OLSInfluence(res_ols)
#print np.max(np.abs(lev['DFFITS'] - infl.dffits[0]))
#print np.max(np.abs(lev['leverage'] - infl.hat_matrix_diag))
#print np.max(np.abs(lev['influence'] - infl.influence)) #just added this based on Gretl
#just rough test, low decimal in Gretl output,
assert_almost_equal(lev['residual'], res.resid, decimal=3)
assert_almost_equal(lev['DFFITS'], infl.dffits[0], decimal=3)
assert_almost_equal(lev['leverage'], infl.hat_matrix_diag, decimal=3)
assert_almost_equal(lev['influence'], infl.influence, decimal=4)
def grangercausalitytests(x, maxlag, addconst=True, verbose=True):
'''four tests for granger causality of 2 timeseries
all four tests give similar results
`params_ftest` and `ssr_ftest` are equivalent based of F test which is
identical to lmtest:grangertest in R
Parameters
----------
x : array, 2d, (nobs,2)
data for test whether the time series in the second column Granger
causes the time series in the first column
maxlag : integer
the Granger causality test results are calculated for all lags up to
maxlag
verbose : bool
print results if true
Returns
-------
results : dictionary
all test results, dictionary keys are the number of lags. For each
lag the values are a tuple, with the first element a dictionary with
teststatistic, pvalues, degrees of freedom, the second element are
the OLS estimation results for the restricted model, the unrestricted
model and the restriction (contrast) matrix for the parameter f_test.
Notes
-----
TODO: convert to class and attach results properly
The Null hypothesis for grangercausalitytests is that the time series in
the second column, x2, Granger causes the time series in the first column,
x1. This means that past values of x2 have a statistically significant
effect on the current value of x1, taking also past values of x1 into
account, as regressors. We reject the null hypothesis of x2 Granger
causing x1 if the pvalues are below a desired size of the test.
'params_ftest', 'ssr_ftest' are based on F test
'ssr_chi2test', 'lrtest' are based on chi-square test
'''
from scipy import stats # lazy import
resli = {}
for mlg in range(1, maxlag+1):
result = {}
if verbose:
print '\nGranger Causality'
print 'number of lags (no zero)', mlg
mxlg = mlg #+ 1 # Note number of lags starting at zero in lagmat
# create lagmat of both time series
dta = lagmat2ds(x, mxlg, trim='both', dropex=1)
#add constant
if addconst:
dtaown = add_constant(dta[:,1:mxlg+1])
dtajoint = add_constant(dta[:,1:])
else:
raise ValueError('Not Implemented')
dtaown = dta[:,1:mxlg]
dtajoint = dta[:,1:]
#run ols on both models without and with lags of second variable
res2down = OLS(dta[:,0], dtaown).fit()
res2djoint = OLS(dta[:,0], dtajoint).fit()
#print results
#for ssr based tests see: http://support.sas.com/rnd/app/examples/ets/granger/index.htm
#the other tests are made-up
# Granger Causality test using ssr (F statistic)
fgc1 = (res2down.ssr-res2djoint.ssr)/res2djoint.ssr/(mxlg)*res2djoint.df_resid
if verbose:
print 'ssr based F test: F=%-8.4f, p=%-8.4f, df_denom=%d, df_num=%d' % \
(fgc1, stats.f.sf(fgc1, mxlg, res2djoint.df_resid), res2djoint.df_resid, mxlg)
result['ssr_ftest'] = (fgc1, stats.f.sf(fgc1, mxlg, res2djoint.df_resid), res2djoint.df_resid, mxlg)
# Granger Causality test using ssr (ch2 statistic)
fgc2 = res2down.nobs*(res2down.ssr-res2djoint.ssr)/res2djoint.ssr
if verbose:
print 'ssr based chi2 test: chi2=%-8.4f, p=%-8.4f, df=%d' % \
(fgc2, stats.chi2.sf(fgc2, mxlg), mxlg)
result['ssr_chi2test'] = (fgc2, stats.chi2.sf(fgc2, mxlg), mxlg)
#likelihood ratio test pvalue:
lr = -2*(res2down.llf-res2djoint.llf)
if verbose:
print 'likelihood ratio test: chi2=%-8.4f, p=%-8.4f, df=%d' % \
(lr, stats.chi2.sf(lr, mxlg), mxlg)
result['lrtest'] = (lr, stats.chi2.sf(lr, mxlg), mxlg)
# F test that all lag coefficients of exog are zero
rconstr = np.column_stack((np.zeros((mxlg-1,mxlg-1)), np.eye(mxlg-1, mxlg-1),\
np.zeros((mxlg-1, 1))))
rconstr = np.column_stack((np.zeros((mxlg,mxlg)), np.eye(mxlg, mxlg),\
np.zeros((mxlg, 1))))
ftres = res2djoint.f_test(rconstr)
if verbose:
print 'parameter F test: F=%-8.4f, p=%-8.4f, df_denom=%d, df_num=%d' % \
(ftres.fvalue, ftres.pvalue, ftres.df_denom, ftres.df_num)
result['params_ftest'] = (np.squeeze(ftres.fvalue)[()],
np.squeeze(ftres.pvalue)[()],
ftres.df_denom, ftres.df_num)
resli[mxlg] = (result, [res2down, res2djoint, rconstr])
return resli
