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| From | Hind Sbihi <sbihi@interchange.ubc.ca> |
| To | statalist@hsphsun2.harvard.edu |
| Subject | st: choosing how to collapse very large datasets |
| Date | Thu, 21 Oct 2010 20:14:24 -0700 (PDT) |
Hello stata users The data I have collected has physiological measurements (variables in col 3 to 7) collected at 256Hz while study participants listen to a song and give the song a rating (last column). Because of the chosen frequency we generated 256 observations per second. Every study participant (n=50) listens to 45 second excerpt for each of 37 songs. The volume of the data set is simply overwhelming at this stage and I am considering different options for starting at least to visualize the data (e.g. rating vs. physiologic responses) before doing any analysis. My question is: how can I aggregate the data? Collapse() seems to be the appropriate command but I am wondering which arguments should go in the command. Below is a snapshot of what the data looks like for the first song for one participant. time songid hr hraccel scr dscr emg resprate skintemp rating 0 1 000063.73 -00000.87 000001.72 -00000.00 000003.49 000050.44 000028.15 4 .0039063 1 000063.73 -00000.87 000001.72 -00000.00 000003.49 000050.44 000028.15 4 .0078125 1 000063.73 -00000.87 000001.72 -00000.00 000003.49 000050.44 000028.15 4 .011719 1 000063.73 -00000.87 000001.72 -00000.00 000003.49 000050.44 000028.15 4 .015625 1 000063.73 -00000.87 000001.72 -00000.00 000003.49 000050.44 000028.15 4 .019531 1 000063.73 -00000.87 000001.72 -00000.00 000003.49 000050.44 000028.15 4 .023438 1 000063.73 -00000.87 000001.72 -00000.00 000003.49 000050.44 000028.15 4 .027344 1 000063.73 -00000.87 000001.72 -00000.00 000003.48 000050.44 000028.15 4 .03125 1 000063.73 -00000.87 000001.72 -00000.00 000003.48 000050.44 000028.15 4 .035156 1 000063.73 -00000.87 000001.72 -00000.00 000003.48 000050.43 000028.15 4 Many thanks in advance for your suggestions. Hind * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/