The data is linked to from the course website represent data collected from the accelerometers from the Samsung Galaxy S smartphone. A full description is available at the site where the data was obtained:
http://archive.ics.uci.edu/ml/datasets/Human+Activity+Recognition+Using+Smartphones
Please read the README file for details around different data files associted in this project.
The R script called run_analysis.R does the following.
Merges the training and the test sets to create one data set.
Extracts only the measurements on the mean and standard deviation for each measurement.
Uses descriptive activity names to name the activities in the data set
Appropriately labels the data set with descriptive variable names.
From the data set in step 4, it creates a second, independent tidy data set with the average of each variable for each activity and each subject.
The project assumes that current working directory includes unzipped data directory.