xtregression

[Hanim Yassin]

Hi all,
I have a question regarding the analysis I`m using. I have to perform xtreg analysis on my data to measure if there is an increase on VAS during a given timeline (20-105 min.) when giving one of six different stimuli to a group of participants. The time variable is given in minutes (from 20min - 105) and VAS is measured every 5 min.. I want to see if VAS increases with time especially between 45 – 60min and 60-75min. I have a list of the commands I have to type to get an output table and run the analysis, but there seems to be a problem with the way I have listed my time values? This is a (short) example of the way I have listed the time variable (cap. is one of 6 applied stimuli.):
VAS stimulation time id
3 cap 20 1
4 cap 25 1
4.5 cap 30 1
5 cap 35 1
5 cap 40 1
5.5 cap 45 1

kind regards,
Hanim

[Carole J. Wilson]

Please read the FAQ. Use dataex to post an example of your data. Tell us exactly what you typed into Stata and the exact output that Stata gave you. Put this code in code delimiters. All of this is described in the FAQ.