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Re: st: Re: How to deal with missing standard error for ivprobit


From   Nick Cox <[email protected]>
To   [email protected]
Subject   Re: st: Re: How to deal with missing standard error for ivprobit
Date   Fri, 18 Mar 2011 01:30:47 +0000

You tell us nothing else about these variables. Also, you are chopping
all details that convey sample size. Same advice: simplify your model!

Nick

On Thu, Mar 17, 2011 at 9:43 PM, xueliansharon <[email protected]> wrote:

> The following is the command I used:
>
> ivprobit y x1 x2 (z1 z2 z3 z4 z5= I1 I2 I3 I4 I5 I6 I7 I8 I9 I10), tech(dfp)
> nrtol(1e-5) showtolerance
>
> Here, y is the dependent variable, x1 and x2 are exogenous variables, z1-z5
> are five endogenous variables (each of them is standardized to have mean 0,
> variance 1), I1-I10 are instruments, but all of the instruments (I1-I10) are
> dummy variables.
>
> Then I got the results like:
>
>
> ------------------------------------------------------------------------------
>             |      Coef.   Std. Err.      z    P>|z|     [95% Conf.
> Interval]
> -------------+----------------------------------------------------------------
> Y     |
>   z1 |   .4000544   .1430333     2.80   0.005     .1197143    .6803945
>   z2 |  -.0470843   .2059814    -0.23   0.819    -.4508004    .3566317
>   z3 |   .3759035   .1411249     2.66   0.008     .0993037    .6525032
>   z4 |  -.4955611          .        .       .            .           .
>   z5 |   -1.05645    .128653    -8.21   0.000    -1.308606   -.8042952
>
> Please note that the standard error for z4 is missing.
> What's more confusing is that when I ask to show the first-stage results,
> the standard errors for I1 and I2 in the equation of z1 (here, I mean the
> first-stage equation with z1 as the dependent variable) are also missing.
>
> I really can't understand why such things happen. Can anybody tell me how to
> deal with such missing standard errors?

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