We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
API/DOCS: newer correlation tools are missing in api and docs
`stats.api` and http://www.statsmodels.org/dev/stats.html#moment-helpers
only shows the original functions, not those added by Kerby

(I'm trying to figure out where we should put new correlation and covariance function, hypothesis tests, robust, regularized covariance and correlation.)


--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `statsmodels/stats/api.py`
Content:
```
1 # pylint: disable=W0611
2 from . import diagnostic
3 from .diagnostic import (
4             acorr_ljungbox, acorr_breusch_godfrey,
5             CompareCox, compare_cox, CompareJ, compare_j,
6             HetGoldfeldQuandt, het_goldfeldquandt,
7             het_breuschpagan, het_white, het_arch,
8             linear_harvey_collier, linear_rainbow, linear_lm,
9             breaks_cusumolsresid, breaks_hansen, recursive_olsresiduals,
10             unitroot_adf,
11             normal_ad, lilliefors,
12              # deprecated because of misspelling:
13             lillifors, het_breushpagan, acorr_breush_godfrey
14             )
15 
16 from . import multicomp
17 from .multitest import (multipletests, fdrcorrection, fdrcorrection_twostage)
18 from .multicomp import tukeyhsd
19 from . import gof
20 from .gof import (powerdiscrepancy, gof_chisquare_discrete,
21                   chisquare_effectsize)
22 from . import stattools
23 from .stattools import durbin_watson, omni_normtest, jarque_bera
24 
25 from . import sandwich_covariance
26 from .sandwich_covariance import (
27             cov_cluster, cov_cluster_2groups, cov_nw_panel,
28             cov_hac, cov_white_simple,
29             cov_hc0, cov_hc1, cov_hc2, cov_hc3,
30             se_cov
31             )
32 
33 from .weightstats import (DescrStatsW, CompareMeans, ttest_ind, ttost_ind,
34                          ttost_paired, ztest, ztost, zconfint)
35 
36 from .proportion import (binom_test_reject_interval, binom_test,
37             binom_tost, binom_tost_reject_interval,
38             power_binom_tost, power_ztost_prop,
39             proportion_confint, proportion_effectsize,
40             proportions_chisquare, proportions_chisquare_allpairs,
41             proportions_chisquare_pairscontrol, proportions_ztest,
42             proportions_ztost)
43 
44 from .power import (TTestPower, TTestIndPower, GofChisquarePower,
45                     NormalIndPower, FTestAnovaPower, FTestPower,
46                     tt_solve_power, tt_ind_solve_power, zt_ind_solve_power)
47 
48 from .descriptivestats import Describe
49 
50 from .anova import anova_lm
51 
52 from . import moment_helpers
53 from .correlation_tools import corr_nearest, corr_clipped, cov_nearest
54 
55 from statsmodels.sandbox.stats.runs import (Runs, runstest_1samp, runstest_2samp)
56 
57 from statsmodels.stats.contingency_tables import (mcnemar, cochrans_q,
58                                                   SquareTable,
59                                                   Table2x2,
60                                                   Table,
61                                                   StratifiedTable)
62
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/statsmodels/stats/api.py b/statsmodels/stats/api.py
--- a/statsmodels/stats/api.py
+++ b/statsmodels/stats/api.py
@@ -39,7 +39,7 @@
             proportion_confint, proportion_effectsize,
             proportions_chisquare, proportions_chisquare_allpairs,
             proportions_chisquare_pairscontrol, proportions_ztest,
-            proportions_ztost)
+            proportions_ztost, multinomial_proportions_confint)
 
 from .power import (TTestPower, TTestIndPower, GofChisquarePower,
                     NormalIndPower, FTestAnovaPower, FTestPower,
@@ -50,7 +50,9 @@
 from .anova import anova_lm
 
 from . import moment_helpers
-from .correlation_tools import corr_nearest, corr_clipped, cov_nearest
+from .correlation_tools import (corr_clipped, corr_nearest,
+            corr_nearest_factor, corr_thresholded, cov_nearest,
+            cov_nearest_factor_homog, FactoredPSDMatrix)
 
 from statsmodels.sandbox.stats.runs import (Runs, runstest_1samp, runstest_2samp)

{"golden_diff": "diff --git a/statsmodels/stats/api.py b/statsmodels/stats/api.py\n--- a/statsmodels/stats/api.py\n+++ b/statsmodels/stats/api.py\n@@ -39,7 +39,7 @@\n             proportion_confint, proportion_effectsize,\n             proportions_chisquare, proportions_chisquare_allpairs,\n             proportions_chisquare_pairscontrol, proportions_ztest,\n-            proportions_ztost)\n+            proportions_ztost, multinomial_proportions_confint)\n \n from .power import (TTestPower, TTestIndPower, GofChisquarePower,\n                     NormalIndPower, FTestAnovaPower, FTestPower,\n@@ -50,7 +50,9 @@\n from .anova import anova_lm\n \n from . import moment_helpers\n-from .correlation_tools import corr_nearest, corr_clipped, cov_nearest\n+from .correlation_tools import (corr_clipped, corr_nearest,\n+            corr_nearest_factor, corr_thresholded, cov_nearest,\n+            cov_nearest_factor_homog, FactoredPSDMatrix)\n \n from statsmodels.sandbox.stats.runs import (Runs, runstest_1samp, runstest_2samp)\n", "issue": "API/DOCS: newer correlation tools are missing in api and docs\n`stats.api` and http://www.statsmodels.org/dev/stats.html#moment-helpers\nonly shows the original functions, not those added by Kerby\n\n(I'm trying to figure out where we should put new correlation and covariance function, hypothesis tests, robust, regularized covariance and correlation.)\n\n", "before_files": [{"content": "# pylint: disable=W0611\nfrom . import diagnostic\nfrom .diagnostic import (\n            acorr_ljungbox, acorr_breusch_godfrey,\n            CompareCox, compare_cox, CompareJ, compare_j,\n            HetGoldfeldQuandt, het_goldfeldquandt,\n            het_breuschpagan, het_white, het_arch,\n            linear_harvey_collier, linear_rainbow, linear_lm,\n            breaks_cusumolsresid, breaks_hansen, recursive_olsresiduals,\n            unitroot_adf,\n            normal_ad, lilliefors,\n             # deprecated because of misspelling:\n            lillifors, het_breushpagan, acorr_breush_godfrey\n            )\n\nfrom . import multicomp\nfrom .multitest import (multipletests, fdrcorrection, fdrcorrection_twostage)\nfrom .multicomp import tukeyhsd\nfrom . import gof\nfrom .gof import (powerdiscrepancy, gof_chisquare_discrete,\n                  chisquare_effectsize)\nfrom . import stattools\nfrom .stattools import durbin_watson, omni_normtest, jarque_bera\n\nfrom . import sandwich_covariance\nfrom .sandwich_covariance import (\n            cov_cluster, cov_cluster_2groups, cov_nw_panel,\n            cov_hac, cov_white_simple,\n            cov_hc0, cov_hc1, cov_hc2, cov_hc3,\n            se_cov\n            )\n\nfrom .weightstats import (DescrStatsW, CompareMeans, ttest_ind, ttost_ind,\n                         ttost_paired, ztest, ztost, zconfint)\n\nfrom .proportion import (binom_test_reject_interval, binom_test,\n            binom_tost, binom_tost_reject_interval,\n            power_binom_tost, power_ztost_prop,\n            proportion_confint, proportion_effectsize,\n            proportions_chisquare, proportions_chisquare_allpairs,\n            proportions_chisquare_pairscontrol, proportions_ztest,\n            proportions_ztost)\n\nfrom .power import (TTestPower, TTestIndPower, GofChisquarePower,\n                    NormalIndPower, FTestAnovaPower, FTestPower,\n                    tt_solve_power, tt_ind_solve_power, zt_ind_solve_power)\n\nfrom .descriptivestats import Describe\n\nfrom .anova import anova_lm\n\nfrom . import moment_helpers\nfrom .correlation_tools import corr_nearest, corr_clipped, cov_nearest\n\nfrom statsmodels.sandbox.stats.runs import (Runs, runstest_1samp, runstest_2samp)\n\nfrom statsmodels.stats.contingency_tables import (mcnemar, cochrans_q,\n                                                  SquareTable,\n                                                  Table2x2,\n                                                  Table,\n                                                  StratifiedTable)\n", "path": "statsmodels/stats/api.py"}], "after_files": [{"content": "# pylint: disable=W0611\nfrom . import diagnostic\nfrom .diagnostic import (\n            acorr_ljungbox, acorr_breusch_godfrey,\n            CompareCox, compare_cox, CompareJ, compare_j,\n            HetGoldfeldQuandt, het_goldfeldquandt,\n            het_breuschpagan, het_white, het_arch,\n            linear_harvey_collier, linear_rainbow, linear_lm,\n            breaks_cusumolsresid, breaks_hansen, recursive_olsresiduals,\n            unitroot_adf,\n            normal_ad, lilliefors,\n             # deprecated because of misspelling:\n            lillifors, het_breushpagan, acorr_breush_godfrey\n            )\n\nfrom . import multicomp\nfrom .multitest import (multipletests, fdrcorrection, fdrcorrection_twostage)\nfrom .multicomp import tukeyhsd\nfrom . import gof\nfrom .gof import (powerdiscrepancy, gof_chisquare_discrete,\n                  chisquare_effectsize)\nfrom . import stattools\nfrom .stattools import durbin_watson, omni_normtest, jarque_bera\n\nfrom . import sandwich_covariance\nfrom .sandwich_covariance import (\n            cov_cluster, cov_cluster_2groups, cov_nw_panel,\n            cov_hac, cov_white_simple,\n            cov_hc0, cov_hc1, cov_hc2, cov_hc3,\n            se_cov\n            )\n\nfrom .weightstats import (DescrStatsW, CompareMeans, ttest_ind, ttost_ind,\n                         ttost_paired, ztest, ztost, zconfint)\n\nfrom .proportion import (binom_test_reject_interval, binom_test,\n            binom_tost, binom_tost_reject_interval,\n            power_binom_tost, power_ztost_prop,\n            proportion_confint, proportion_effectsize,\n            proportions_chisquare, proportions_chisquare_allpairs,\n            proportions_chisquare_pairscontrol, proportions_ztest,\n            proportions_ztost, multinomial_proportions_confint)\n\nfrom .power import (TTestPower, TTestIndPower, GofChisquarePower,\n                    NormalIndPower, FTestAnovaPower, FTestPower,\n                    tt_solve_power, tt_ind_solve_power, zt_ind_solve_power)\n\nfrom .descriptivestats import Describe\n\nfrom .anova import anova_lm\n\nfrom . import moment_helpers\nfrom .correlation_tools import (corr_clipped, corr_nearest,\n            corr_nearest_factor, corr_thresholded, cov_nearest,\n            cov_nearest_factor_homog, FactoredPSDMatrix)\n\nfrom statsmodels.sandbox.stats.runs import (Runs, runstest_1samp, runstest_2samp)\n\nfrom statsmodels.stats.contingency_tables import (mcnemar, cochrans_q,\n                                                  SquareTable,\n                                                  Table2x2,\n                                                  Table,\n                                                  StratifiedTable)\n", "path": "statsmodels/stats/api.py"}]}