Hi all:
I'm conducting a study examining whether a specific intervention improves the quality of performance ratings made by managers regarding employees.
What I have is these performance ratings and also data regarding the employees' "objective performance." Objective performance is my criterion to assess the quality of the performance ratings. So, the larger the relationship between performance ratings and objective performance, the better their quality (akin to the notion of "criterion validity" in educational or organizational psychology).
I have data at two points in time, t1 and t2, regarding the same employees and the same managers (employees are clustered within managers). Our intervention was aimed at improving the performance ratings; this was done after t1 and before t2. So, what I'd like to test is whether the relationship between objective performance and the performance ratings at time 2 was larger than the relationship at time 1.
How would you set up this in Stata?
One way I was thinking about is the following:
xtreg y c.x##i.time, vce(cluster id_e id_s)
where y is objective performance, x is the performance ratings, time is a dummy variable (time1 vs time2), id_e is the employees' identifier and id_s is the supervisors' identifier.
What is the difference between the above vs. the following, where I add the fixed effects (fe) command?
xtreg y c.x##i.time, fe vce(cluster id_e id_s)
Remember that the same employees received the ratings by the same supervisors at both times, and we also have measures of their objective performance at these two times (4 measures in total for all employees).
Any advice or comment (even if it's an entirely different regression or command) is greatly appreciated.
Ed
I'm conducting a study examining whether a specific intervention improves the quality of performance ratings made by managers regarding employees.
What I have is these performance ratings and also data regarding the employees' "objective performance." Objective performance is my criterion to assess the quality of the performance ratings. So, the larger the relationship between performance ratings and objective performance, the better their quality (akin to the notion of "criterion validity" in educational or organizational psychology).
I have data at two points in time, t1 and t2, regarding the same employees and the same managers (employees are clustered within managers). Our intervention was aimed at improving the performance ratings; this was done after t1 and before t2. So, what I'd like to test is whether the relationship between objective performance and the performance ratings at time 2 was larger than the relationship at time 1.
How would you set up this in Stata?
One way I was thinking about is the following:
xtreg y c.x##i.time, vce(cluster id_e id_s)
where y is objective performance, x is the performance ratings, time is a dummy variable (time1 vs time2), id_e is the employees' identifier and id_s is the supervisors' identifier.
What is the difference between the above vs. the following, where I add the fixed effects (fe) command?
xtreg y c.x##i.time, fe vce(cluster id_e id_s)
Remember that the same employees received the ratings by the same supervisors at both times, and we also have measures of their objective performance at these two times (4 measures in total for all employees).
Any advice or comment (even if it's an entirely different regression or command) is greatly appreciated.
Ed
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