help ivcheck

Title

ivcheck -- Choices between IV versus OLS

Syntax

Full syntax

ivcheck depvar [varlist1]
(varlist2=varlist_iv)
[if] [in]
[weight]
[, SAVing(string)
LOW(#)
HIgh(#)
]

All varlists may contain time-series operators;
see varlist.

aweights, and fweights are allowed; see weight.

Contents

Description

Options summary

Saved results

Examples

References

Acknowledgments

Authors

Citation

Description

ivcheck produces a phase diagram that can be used to assess the question
whether the mean squared estimation error with IVs will be larger than that from OLS
given the data at hand. Specifically, given a reasonable lower bound for the OLS bias,
one can confirm whether the IV at hand can produce a better estimate (i.e. with lower bias)
of the true effect parameter than the OLS, without knowing the true level of
contamination in the IV

Options

saving(string) requests that the phase plot be saved using the path/filename
specified in string.

specifies the lower bound on the X-axis on the phase plot. Default in -1.

specifies the higher bound on the X-axis on the phase plot. Default in 1.

Saved results

ivcheck saves the following results in r():

Scalars

r(cuoff_rho_xe) the upper or lower bound of Corr(X,e) beyond which IV at hand is better(

e(rho_zy_x) partial Corr (Z,Y | X W)

e(rho_xz) Corr(X, Z)

Functions

e(sample) marks estimation sample

Examples

. ivcheck y (x=z)

. ivcheck y w (x=z)

References

4.	Basu A. Chan KCG. Can we make smart choices between OLS versus Contaminated IV estimators? Health Economics 2014; 23(4):462-72.

Acknowledgments

The author acknowledges support from the National Institute of Health Research Grants, RC4CA155809 and R01CA155329.

Authors

Anirban Basu, University of Washington, USA
basua@uw.edu

Citation

ivcheck is not an official Stata command. It is a free contribution
to the research community, like a paper. Please cite it as such:

Also see

Online: ivregress, newey;
overid, ivendog, ivhettest, ivreset,
xtivcheck, xtoverid, ranktest,
condivreg (if installed);
est, postest;
regress