For run_analysis script to work your working directory should be set to the directory that contains all neccessary files (tables with data)

Script will load package that is needed for analysis and perform each of the following steps:

1. Read all the tables

2. Merge the training and the test sets to create one data set.

3. Extract only the measurements on the mean and standard deviation for each measurement.

4. Change to descriptive activity names instead of codes

5. Make syntactically valid names to the variables

6. Create a second, independent tidy data set with the average of each variable for each activity and each subject.

Each of these steps is clearly stated in the script.

In addition all variables are described in codebook as well as brief description of the origin of data.