def anova2_lm_single(model, design_info, n_rows, test, pr_test, robust):
"""
ANOVA type II table for one fitted linear model.
Parameters
----------
model : fitted linear model results instance
A fitted linear model
**kwargs**
scale : float
Estimate of variance, If None, will be estimated from the largest
model. Default is None.
test : str {"F", "Chisq", "Cp"} or None
Test statistics to provide. Default is "F".
Notes
-----
Use of this function is discouraged. Use anova_lm instead.
Type II
Sum of Squares compares marginal contribution of terms. Thus, it is
not particularly useful for models with significant interaction terms.
"""
terms_info = design_info.terms[:] # copy
terms_info = _remove_intercept_patsy(terms_info)
names = ['sum_sq', 'df', test, pr_test]
table = DataFrame(np.zeros((n_rows, 4)), columns = names)
cov = _get_covariance(model, None)
robust_cov = _get_covariance(model, robust)
col_order = []
index = []
for i, term in enumerate(terms_info):
# grab all varaibles except interaction effects that contain term
# need two hypotheses matrices L1 is most restrictive, ie., term==0
# L2 is everything except term==0
cols = design_info.slice(term)
L1 = range(cols.start, cols.stop)
L2 = []
term_set = set(term.factors)
for t in terms_info: # for the term you have
other_set = set(t.factors)
if term_set.issubset(other_set) and not term_set == other_set:
col = design_info.slice(t)
# on a higher order term containing current `term`
L1.extend(range(col.start, col.stop))
L2.extend(range(col.start, col.stop))
L1 = np.eye(model.model.exog.shape[1])[L1]
L2 = np.eye(model.model.exog.shape[1])[L2]
if L2.size:
LVL = np.dot(np.dot(L1,robust_cov),L2.T)
from scipy import linalg
orth_compl,_ = linalg.qr(LVL)
r = L1.shape[0] - L2.shape[0]
# L1|2
# use the non-unique orthogonal completion since L12 is rank r
L12 = np.dot(orth_compl[:,-r:].T, L1)
else:
L12 = L1
r = L1.shape[0]
#from IPython.core.debugger import Pdb; Pdb().set_trace()
if test == 'F':
f = model.f_test(L12, cov_p=robust_cov)
table.ix[i][test] = test_value = f.fvalue
table.ix[i][pr_test] = f.pvalue
# need to back out SSR from f_test
table.ix[i]['df'] = r
col_order.append(cols.start)
index.append(term.name())
table.index = Index(index + ['Residual'])
table = table.ix[np.argsort(col_order + [model.model.exog.shape[1]+1])]
# back out sum of squares from f_test
ssr = table[test] * table['df'] * model.ssr/model.df_resid
table['sum_sq'] = ssr
# fill in residual
table.ix['Residual'][['sum_sq','df', test, pr_test]] = (model.ssr,
model.df_resid,
np.nan, np.nan)
return table
def anova2_lm_single(model, design_info, n_rows, test, pr_test, robust):
"""
Anova type II table for one fitted linear model.
Parameters
----------
model : fitted linear model results instance
A fitted linear model
**kwargs**
scale : float
Estimate of variance, If None, will be estimated from the largest
model. Default is None.
test : str {"F", "Chisq", "Cp"} or None
Test statistics to provide. Default is "F".
Notes
-----
Use of this function is discouraged. Use anova_lm instead.
Type II
Sum of Squares compares marginal contribution of terms. Thus, it is
not particularly useful for models with significant interaction terms.
"""
terms_info = design_info.terms[:] # copy
terms_info = _remove_intercept_patsy(terms_info)
names = ['sum_sq', 'df', test, pr_test]
table = DataFrame(np.zeros((n_rows, 4)), columns = names)
cov = _get_covariance(model, None)
robust_cov = _get_covariance(model, robust)
col_order = []
index = []
for i, term in enumerate(terms_info):
# grab all varaibles except interaction effects that contain term
# need two hypotheses matrices L1 is most restrictive, ie., term==0
# L2 is everything except term==0
cols = design_info.slice(term)
L1 = lrange(cols.start, cols.stop)
L2 = []
term_set = set(term.factors)
for t in terms_info: # for the term you have
other_set = set(t.factors)
if term_set.issubset(other_set) and not term_set == other_set:
col = design_info.slice(t)
# on a higher order term containing current `term`
L1.extend(lrange(col.start, col.stop))
L2.extend(lrange(col.start, col.stop))
L1 = np.eye(model.model.exog.shape[1])[L1]
L2 = np.eye(model.model.exog.shape[1])[L2]
if L2.size:
LVL = np.dot(np.dot(L1,robust_cov),L2.T)
from scipy import linalg
orth_compl,_ = linalg.qr(LVL)
r = L1.shape[0] - L2.shape[0]
# L1|2
# use the non-unique orthogonal completion since L12 is rank r
L12 = np.dot(orth_compl[:,-r:].T, L1)
else:
L12 = L1
r = L1.shape[0]
#from IPython.core.debugger import Pdb; Pdb().set_trace()
if test == 'F':
f = model.f_test(L12, cov_p=robust_cov)
table.loc[table.index[i], test] = test_value = f.fvalue
table.loc[table.index[i], pr_test] = f.pvalue
# need to back out SSR from f_test
table.loc[table.index[i], 'df'] = r
col_order.append(cols.start)
index.append(term.name())
table.index = Index(index + ['Residual'])
table = table.iloc[np.argsort(col_order + [model.model.exog.shape[1]+1])]
# back out sum of squares from f_test
ssr = table[test] * table['df'] * model.ssr/model.df_resid
table['sum_sq'] = ssr
# fill in residual
table.loc['Residual', ['sum_sq','df', test, pr_test]] = (model.ssr,
model.df_resid,
np.nan, np.nan)
return table
