IDEAS home Printed from
MyIDEAS: Log in (now much improved!) to save this paper

Inference on a Structural Parameter in Instrumental Variables Regression with Weak Instruments

Listed author(s):
  • Jiahui Wang

    (Department of Economics University of Washington)

  • Eric Zivot

In this paper we consider the problem of making inference on a structural parameter in instrumental variables regression when the instruments are only weakly correlated with the endogenous explanatory variables. Adopting a local-to-zero assumption as in Staiger and Stock (1994) on the coefficients of the instruments in the first stage equation, the asymptotic distributions of various test statistics are derived under a limited information framework. We show that Wald-type test statistics are not pivotal, thus (1-a)*100% confidence intervals implied by those test statistics can have zero coverage probability if the standard asymptotic distribution theory is used. In contrast, the likelihood type test statistics are pivotal when the model is just identified, thus providing valid confidence intervals. Even the model is overidentified, we show that the distributions of the likelihood type test statistics are bounded above by a Chi-Square distribution with degrees of freedom given by the number of instruments. Hence, we can always invert the likelihood type test statistics to obtain valid, although conservative, confidence intervals. The confidence intervals obtained by using this bounding distribution are compared with those obtained by using the standard Chi-Square 1 asymptotic distribution and an alternative bounding distribution, a transformation of the distribution of the Wilks statistic, suggested by Dufour (1994) . Confidence intervals based on our Chi-Square bounding distribution are shown to be tighter than those based on the Wilks bounding distribution by Monte Carlo experiments.

If you experience problems downloading a file, check if you have the proper application to view it first. In case of further problems read the IDEAS help page. Note that these files are not on the IDEAS site. Please be patient as the files may be large.

File URL:
Download Restriction: no

File URL:
Download Restriction: no

Paper provided by EconWPA in its series Econometrics with number 9610005.

in new window

Length: 30 pages
Date of creation: 24 Oct 1996
Handle: RePEc:wpa:wuwpem:9610005
Note: Type of Document - Adobe pdf file; prepared on Unix using TeX; to print on Postscript; pages: 30; figures: 5 pages of tables. 30 pages, Adobe pdf file translated from Unix TeX file.
Contact details of provider: Web page:

No references listed on IDEAS
You can help add them by filling out this form.

This item is not listed on Wikipedia, on a reading list or among the top items on IDEAS.

When requesting a correction, please mention this item's handle: RePEc:wpa:wuwpem:9610005. See general information about how to correct material in RePEc.

For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: (EconWPA)

If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

If references are entirely missing, you can add them using this form.

If the full references list an item that is present in RePEc, but the system did not link to it, you can help with this form.

If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your profile, as there may be some citations waiting for confirmation.

Please note that corrections may take a couple of weeks to filter through the various RePEc services.

This information is provided to you by IDEAS at the Research Division of the Federal Reserve Bank of St. Louis using RePEc data.