# Thread: inteff-command after fitting a probit model in Stata -> Graph with interaction effect

1. ## inteff-command after fitting a probit model in Stata -> Graph with interaction effect

Hello,

(For people who are familiar with the inteff-command, skip the first two paragraphs and just read the third paragraph)

I run a probit model with the interaction term GindexHHI and the separate terms Gindex and HHI (Gindex = governance strength; HHI = industry concentration). All other variables are performance control variables. The dependent variable takeovercompleted equals takeover likelihood, coded as a binary dummy variable.
-> probit takeovercompleted SalesGrowth Liquidity DEratio MBratio PEratio Size Gindex HHI GindexHHI

After the probit model, I compute the marginal effect of the interaction term GindexHHI. I do this by applying the inteff-command after the probit model which computes the cross-partial derivative of the interaction term (which corresponds to the correct marginal effect of the interaction term)
->inteff takeovercompleted SalesGrowth Liquidity DEratio MBratio PEratio Size Gindex HHI GindexHHI

I get a graph with the marginal effect of the interaction term (interaction effect in %) and a graph with z-statistics of the interaction term to derive the stat. sign.

Firstly, Stata shows the graph with the interaction effect and then overwrites this graph with the graph for the z-statistics of the interaction effect. However, I need to show both graphs in my research. I can only copy the graph with z-statistics at the moment. How can I tell Stata to show both graphs or to show them separately?

Example of the output (standard error omitted)

Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
interaction effect | 136 -.2959831 .1422207 -.3679685 .290872
z-statistic | 136 -1.288604 .800488 -2.093989 2.513241

2. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

I've been looking for a command like inteff. But it does not seem to work for me, neither for mlogit or mprobit. I've got STATA 11. OnT: Sorry, can't help.

3. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

ok, thanks anyway...I just use a probit model and it works, disregarding the small problem that I described above... I do not know what is mprobit at all...
There is a paper called: "Computing interaction effects and standard errors in logit and probit models", The Stata Journal (2004), Vol. 4, No. 2, by Norton, Wang and Ai

4. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

Thanks, I'll check it out. mprobit is a multinomial probit model. A model where the DV takes on more than two values.

5. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

Ok, I think this paper only refers to "normal" probit and logit models...but I am not totally sure..

6. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

I haven't used -inteff- but it looks like you need to use the savegraph1() and savegraph2() options documented in -help inteff-

7. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

Hi bukharin,

I tried that with savegraph1 and savegraph2, but it does not work, I get the error message r199 below.
I use "F:\MASTER THESE MAASTRICHT Oct2011 - Backup\Most essential data\Stata11.2" as my current working directory...

Output:
inteff takeovercompleted Gindex HHI GindexHHI SalesGrowth Liquidity DEratio MBratio PEratio Size Buseq Chems Durbl Enrgy Hlth Manuf Mo
> ney Nodur Other Shops Telcm Utils
Probit with two continuous variables interacted
(10359 observations deleted)

Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
_probit_ie | 100 -.9049926 .5553251 -1.990601 1.025768
_probit_se | 100 .6795854 .2501268 3.65e-21 1.491133
_probit_z | 100 -1.243099 .7676063 -2.290685 1.018358

.
. savegraph1(F:\MASTER THESE MAASTRICHT Oct2011 - Backup\Most essential data\Stata11.2\Figure1ieinperc, replace)
unrecognized command: savegraph1
r(199);

.
. savegraph2(F:\MASTER THESE MAASTRICHT Oct2011 - Backup\Most essential data\Stata11.2\Figure1ieinperc, replace)
unrecognized command: savegraph2
r(199);

8. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

No, savegraph1() and savegraph(2) are options for -inteff- - you need to use them after a comma on the same line as the -inteff- command. See -help language-

9. ## Re: inteff-command after fitting a probit model in Stata -> Graph with interaction ef

yes indeed. It works now. Thanks a lot.

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