<div dir="ltr">You can also do a modeling approach based on two-stage least squares. In your case, this might be the easiest. Take a look at page at the end of page 783 and the beginning of page 784 of this paper for discussion: <a href="http://imai.princeton.edu/research/files/mediationP.pdf">http://imai.princeton.edu/research/files/mediationP.pdf</a></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><font size="1">Kosuke Imai <br>Professor, Department of Politics <br>Center for Statistics and Machine Learning<br>Princeton University<br><a href="http://imai.princeton.edu" target="_blank">http://imai.princeton.edu</a> </font></div></div></div>
<br><div class="gmail_quote">On Sat, Aug 12, 2017 at 1:38 AM, Teppei Yamamoto <span dir="ltr"><<a href="mailto:teppei@mit.edu" target="_blank">teppei@mit.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Hi Greg,<br>
<br>
The function can produce those values for the bounds when your data are not consistent with the identification assumptions, such as the consistency assumption or the exclusion restrictions. It could also be due to some mistake in the data (e.g. miscoding in a variable). If you send me your code and the dataset (maybe a subset that reproduces the same problem, if you cannot send the whole thing), I'll be happy to look into it to the extent I can.<br>
<br>
We unfortunately don't have a plan to extend it to a continuous outcome variable, primarily because our theoretical framework doesn't simply generalize to such a setup. There are alternative approaches that could potentially achieve what we need, though, so we (or someone else) might someday get to it -- not on our immediate agenda unfortunately!<br>
<br>
Best,<br>
Teppei<br>
<br>
------------------------------<wbr>------------<br>
Teppei Yamamoto<br>
<br>
Associate Professor of Political Science<br>
Alfred Henry and Jean Morrison Hayes Chair<br>
Massachusetts Institute of Technology<br>
<br>
<a href="http://web.mit.edu/teppei/www/" rel="noreferrer" target="_blank">http://web.mit.edu/teppei/www/</a><br>
------------------------------<wbr>------------<div><div class="h5"><br>
<br>
On 8/11/17 08:17, GREG PORUMBESCU wrote:<br>
</div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
Dear All,<br>
<br>
My colleagues and I are trying to analyze data coming from a parallel encouragement design using the mediate.ped function in the mediate R package. Our encouragement, time, has three levels: 1 (long time), -1 (short time) and 0 (no time limit). We have two questions:<br>
<br>
1) We have followed the instructions provided in Tingley et al. 2014, but when we run the syntax, the lower and upper bound confidence intervals on all of the ACME report 0. These estimates hold even when we used different (binary) mediators. The code we are using and the output is as follows:<br>
<br>
> ped<- mediate.ped("PERFORMANCE_binar<wbr>y", "sum_obund_new_binary", "negframe", "time", DFC_coded)<br>
> summary(ped)<br>
<br>
Design-Based Causal Mediation Analysis<br>
<br>
Parallel Encouragement Design<br>
<br>
Lower Bound Upper Bound<br>
Population ACME (control) 0 0<br>
Complier ACME (control) 0 0<br>
Population ACME (treated) 0 0<br>
Complier ACME (treated) 0 0<br>
<br>
Sample Size Used: 610<br>
<br>
<br>
Would you have any idea what is causing our estimates to behave this way? Any advice on how to resolve this issue?<br>
<br>
2) In our code, we transform our outcome variable, PERFORMANCE, into a binary variable in order to run mediate.ped, as the instructions indicate. However, is there any way to run mediate.ped with a continuous outcome variable? If not, are there any plans to allow for this in the future?<br>
<br>
Many thanks,<br>
<br>
Greg<br>
<br>
Best wishes,<br>
<br>
Gregory A. Porumbescu<br>
Assistant Professor<br>
School of Public Affairs and Administration<br>
Rutgers University Newark<br>
<a href="https://spaa.newark.rutgers.edu/gregory-porumbescu" rel="noreferrer" target="_blank">https://spaa.newark.rutgers.ed<wbr>u/gregory-porumbescu</a><br>
<br>
<a href="https://scholar.google.com/scholar?hl=en&q=gregory+porumbescu&btnG=&as_sdt=1%2C14&as_sdtp=&oq=gre" rel="noreferrer" target="_blank">https://scholar.google.com/sch<wbr>olar?hl=en&q=gregory+porumbesc<wbr>u&btnG=&as_sdt=1%2C14&as_sdtp=<wbr>&oq=gre</a><br>
<br>
<br>
<br></div></div>
ᐧ<br>
<br>
<br>
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