CodeBook.md

Study Design

The raw data has been subset by taking the mean and standard-deviation pairs, where present, of the measured and estimates/derived variables e.g. tBodyAcc-mean() and tBodyAcc-std(), but not angle(tBodyAccMean,gravity).

Each observation is then enriched with the corresponding subject and activity; the activity variable is transformed into a factor-variable, giving more descriptive categorical values.

This subset is then summarized by taking the average of the measured/estimate/derived variable across all windows, grouped by the enriched subject and activity variables, in that order.

Thus there are 180 observations; 1 for each of the 6 activities for each of the 30 subjects.

Code Book

File format

The output file, tidy_data.txt, is a space delimited, wide format file.

It contains 181 lines; 180 observations, as described above, preceeded by one header row

Each variable is described below

Variables

1. subject

• Integer
• Categorical: 1 to 30
• Identifies the subject (person carrying out the actvity) of this observation

2. activity

• Factor
• Categorical: WALKING, WALKING_UPSTAIRS, WALKING_DOWNSTAIRS, SITTING, STANDING, LAYING
• Identifies the activity reflected by this observarion

3. tBodyAcc-mean()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean X-axis body acceleration

4. tBodyAcc-mean()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean Y-axis body acceleration

5. tBodyAcc-mean()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean Z-axis body acceleration

6. tBodyAcc-std()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation X-axis body acceleration

7. tBodyAcc-std()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation Y-axis body acceleration

8. tBodyAcc-std()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation Z-axis body acceleration

9. tGravityAcc-mean()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean X-axis gravity acceleration

10. tGravityAcc-mean()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean Y-axis gravity acceleration

11. tGravityAcc-mean()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean Z-axis gravity acceleration

12. tGravityAcc-std()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation X-axis gravity acceleration

13. tGravityAcc-std()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation Y-axis gravity acceleration

14. tGravityAcc-std()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation Z-axis gravity acceleration

15. tBodyAccJerk-mean()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean X-axis body jerk acceleration

16. tBodyAccJerk-mean()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean Y-axis body jerk acceleration

17. tBodyAccJerk-mean()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean Z-axis body jerk acceleration

18. tBodyAccJerk-std()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation X-axis body jerk acceleration

19. tBodyAccJerk-std()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation Y-axis body jerk acceleration

20. tBodyAccJerk-std()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain standard deviation Z-axis body jerk acceleration

21. tBodyGyro-mean()-X

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean X-axis body rotation

22. tBodyGyro-mean()-Y

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean Y-axis body rotation

23. tBodyGyro-mean()-Z

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean Z-axis body rotation

24. tBodyGyro-std()-X

• Decimal, radians per second (r/s)
• Continuous
• Time domain standard deviation X-axis body rotation

25. tBodyGyro-std()-Y

• Decimal, radians per second (r/s)
• Continuous
• Time domain standard deviation Y-axis body rotation

26. tBodyGyro-std()-Z

• Decimal, radians per second (r/s)
• Continuous
• Time domain standard deviation Z-axis body rotation

27. tBodyGyroJerk-mean()-X

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean X-axis body jerk rotation

28. tBodyGyroJerk-mean()-Y

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean Y-axis body jerk rotation

29. tBodyGyroJerk-mean()-Z

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean Z-axis body jerk rotation

30. tBodyGyroJerk-std()-X

• Decimal, radians per second (r/s)
• Continuous
• Time domain standard deviation X-axis body jerk rotation

31. tBodyGyroJerk-std()-Y

• Decimal, radians per second (r/s)
• Continuous
• Time domain standard deviation Y-axis body jerk rotation

32. tBodyGyroJerk-std()-Z

• Decimal, radians per second (r/s)
• Continuous
• Time domain standard deviation Z-axis body jerk rotation

33. tBodyAccMag-mean()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean magnitude body acceleration

34. tBodyAccMag-std()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain std magnitude body acceleration

35. tGravityAccMag-mean()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean magnitude GravityAcc

36. tGravityAccMag-std()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain std magnitude GravityAcc

37. tBodyAccJerkMag-mean()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain mean magnitude body jerk acceleration

38. tBodyAccJerkMag-std()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Time domain std magnitude body jerk acceleration

39. tBodyGyroMag-mean()

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean magnitude body rotation

40. tBodyGyroMag-std()

• Decimal, radians per second (r/s)
• Continuous
• Time domain std magnitude body rotation

41. tBodyGyroJerkMag-mean()

• Decimal, radians per second (r/s)
• Continuous
• Time domain mean magnitude body jerk rotation

42. tBodyGyroJerkMag-std()

• Decimal, radians per second (r/s)
• Continuous
• Time domain std magnitude body jerk rotation

43. fBodyAcc-mean()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean X-axis body acceleration

44. fBodyAcc-mean()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean Y-axis body acceleration

45. fBodyAcc-mean()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean Z-axis body acceleration

46. fBodyAcc-std()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain standard deviation X-axis body acceleration

47. fBodyAcc-std()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain standard deviation Y-axis body acceleration

48. fBodyAcc-std()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain standard deviation Z-axis body acceleration

49. fBodyAccJerk-mean()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean X-axis body jerk acceleration

50. fBodyAccJerk-mean()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean Y-axis body jerk acceleration

51. fBodyAccJerk-mean()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean Z-axis body jerk acceleration

52. fBodyAccJerk-std()-X

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain standard deviation X-axis body jerk acceleration

53. fBodyAccJerk-std()-Y

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain standard deviation Y-axis body jerk acceleration

54. fBodyAccJerk-std()-Z

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain standard deviation Z-axis body jerk acceleration

55. fBodyGyro-mean()-X

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain mean X-axis body rotation

56. fBodyGyro-mean()-Y

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain mean Y-axis body rotation

57. fBodyGyro-mean()-Z

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain mean Z-axis body rotation

58. fBodyGyro-std()-X

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain standard deviation X-axis body rotation

59. fBodyGyro-std()-Y

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain standard deviation Y-axis body rotation

60. fBodyGyro-std()-Z

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain standard deviation Z-axis body rotation

61. fBodyAccMag-mean()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean magnitude body acceleration

62. fBodyAccMag-std()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain std magnitude body acceleration

63. fBodyBodyAccJerkMag-mean()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain mean magnitude Bodybody jerk acceleration

64. fBodyBodyAccJerkMag-std()

• Decimal, meters per second-squared (m/s^2)
• Continuous
• Frequency domain std magnitude Bodybody jerk acceleration

65. fBodyBodyGyroMag-mean()

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain mean magnitude Bodybody rotation

66. fBodyBodyGyroMag-std()

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain std magnitude Bodybody rotation

67. fBodyBodyGyroJerkMag-mean()

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain mean magnitude Bodybody jerk rotation

68. fBodyBodyGyroJerkMag-std()

• Decimal, radians per second (r/s)
• Continuous
• Frequency domain std magnitude Bodybody jerk rotation