Hello again, Sorry for the confusion, and thank you for your help. The three data sets were collected at night from a single human subject as he slept. (1) The data set "Stages" contains electroencephalogram (EEG) data. The data are divided into 20 second epochs. Each epoch contains one value, the sleep stage. In the example file attached here, the subject fell asleep at epoch 618 and awoke at epoch 2159. (2) The data set "RR_s" contains electrocardiogram (EKG) data. The data are also divided into 20 second epochs; however, in this case, instead of one value per epoch, there are multiple values per epoch. This is because these data reflect all the individual heart beats during each twenty second epoch. (3) The final data set, "HR", contains photoplethysmogram data. In this data set, there is a single mean heart rate value per 60 seconds by clock time. The clock time is synchronized to the start and end of the subject's sleep episode, i.e., clock time 23:25 aligns with the start of epoch 618, and clock time 7:59 aligns with the start of epoch 2159. I need to merge these three data sets into one master data set, such that the epochs and clock times for each observation correctly synchronize. Attached are files containing example data sets. Please let me know if you have any questions. Thank you again for any help. Sincerely, Ian
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