[Mediation-information] Trouble with mediate.ped function in Mediation for R

[GREG PORUMBESCU]

Dear All,

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:

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:

> ped<- mediate.ped("PERFORMANCE_binary", "sum_obund_new_binary",
"negframe", "time", DFC_coded)
> summary(ped)

Design-Based Causal Mediation Analysis

Parallel Encouragement Design

                          Lower Bound Upper Bound
Population ACME (control)           0           0
Complier ACME (control)             0           0
Population ACME (treated)           0           0
Complier ACME (treated)             0           0

Sample Size Used:  610


Would you have any idea what is causing our estimates to behave this way?
Any advice on how to resolve this issue?

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?

Many thanks,

Greg

Best wishes,

Gregory A. Porumbescu
Assistant Professor
School of Public Affairs and Administration
Rutgers University Newark
https://spaa.newark.rutgers.edu/gregory-porumbescu

https://scholar.google.com/scholar?hl=en&q=gregory+porumbescu&btnG=&as_sdt=1%2C14&as_sdtp=&oq=gre



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