-------------------------------------------------------------------------------------------------------------------------------------- log: C:\Documents and Settings\Sandrah Eckel\Desktop\LDA lab1\lab1.log log type: text opened on: 27 Jan 2008, 15:17:10 . . infile week1-week9 using "pigs.data" (48 observations read) . . save "pigs.dta", replace file pigs.dta saved . *load a previously saved version of this data that already has an id variable . . use "pigs.stata.dta", clear . . . . *re-load the dataset we had just saved . . use "pigs.dta", clear . *Genearate the id=observation number . . generate id=_n . . move id week1 . . list +----------------------------------------------------------------------------+ | id week1 week2 week3 week4 week5 week6 week7 week8 week9 | |----------------------------------------------------------------------------| 1. | 1 24 32 39 42.5 48 54.5 61 65 72 | 2. | 2 22.5 30.5 40.5 45 51 58.5 64 72 78 | 3. | 3 22.5 28 36.5 41 47.5 55 61 68 76 | 4. | 4 24 31.5 39.5 44.5 51 56 59.5 64 67 | 5. | 5 24.5 31.5 37 42.5 48 54 58 63 65.5 | |----------------------------------------------------------------------------| 6. | 6 23 30 35.5 41 48 51.5 56.5 63.5 69.5 | 7. | 7 22.5 28.5 36 43.5 47 53.5 59.5 67.5 73.5 | 8. | 8 23.5 30.5 38 41 48.5 55 59.5 66.5 73 | 9. | 9 20 27.5 33 39 43.5 49 54.5 59.5 65 | 10. | 10 25.5 32.5 39.5 47 53 58.5 63 69.5 76 | |----------------------------------------------------------------------------| 11. | 11 24.5 31 40.5 46 51.5 57 62.5 69.5 76 | 12. | 12 24 29 39 44 50.5 57 61.5 68 73.5 | 13. | 13 23.5 30.5 36.5 42 47 55 59 65.5 73 | 14. | 14 21.5 30.5 37 42.5 48 52.5 58.5 63 69.5 | 15. | 15 25 32 38.5 44 51 59 66 75.5 86 | |----------------------------------------------------------------------------| 16. | 16 21.5 28.5 34 39.5 45 51 58 64.5 72.5 | 17. | 17 31 38 48 54 60 62 66.5 75.5 84 | 18. | 18 27.5 32.5 36 43 49.5 52.5 56 61 64 | 19. | 19 30 37 45 51 58 63 67.5 74.5 81 | 20. | 20 26 32 40.5 45.5 52.5 55.5 62.5 69.5 74 | |----------------------------------------------------------------------------| 21. | 21 26 32.5 39.5 44 48 54.5 58 66 73 | 22. | 22 28.5 35.5 41.5 47.5 54 59.5 63.5 71 78.5 | 23. | 23 26.5 34.5 42 48.5 55.5 62 68 76.5 85 | 24. | 24 27.5 33.5 41 45 50.5 56 62.5 71 78 | 25. | 25 22.5 27 33.5 38.5 41 49 56 64 68 | |----------------------------------------------------------------------------| 26. | 26 22 26.5 32.5 38.5 43.5 50.5 56.5 63.5 68.5 | 27. | 27 23.5 29 35.5 40 45 50 56.5 63 67.5 | 28. | 28 22.5 29.5 36.5 42 45 55 61 68 72 | 29. | 29 27.5 34.5 42 47.5 53 63 72 79 85.5 | 30. | 30 23.5 28 33 37 38.5 48 52.5 62 64.5 | |----------------------------------------------------------------------------| 31. | 31 24.5 30 38.5 42 47.5 54 62.5 71.5 77 | 32. | 32 24.5 31.5 40.5 46.5 51.5 61.5 68.5 77.5 84.5 | 33. | 33 24.5 32 39 45 51 55.5 61.5 69 75.5 | 34. | 34 24 32.5 40 48 54.5 61.5 68 74.5 81 | 35. | 35 24 31.5 38.5 44 51.5 57.5 64 72.5 79 | |----------------------------------------------------------------------------| 36. | 36 24.5 32.5 39.5 44.5 52.5 56.5 62 67.5 72.5 | 37. | 37 24.5 32 38.5 44 50 56 63.5 69.5 76 | 38. | 38 25.5 33 41.5 47 55.5 60.5 66.5 77 82 | 39. | 39 25.5 32 39 45.5 51 57.5 63.5 72 78.5 | 40. | 40 25 31 36.5 43 50.5 55 62.5 69 75.5 | |----------------------------------------------------------------------------| 41. | 41 26.5 30.5 33 39 43.5 49.5 56.5 61 65 | 42. | 42 24 32 39 44.5 50 56 63 67.5 74 | 43. | 43 24.5 31 37.5 43.5 48 56 62.5 66.5 70.5 | 44. | 44 27 34.5 42 48.5 53 60 67 73 76 | 45. | 45 31 39 47.5 51 57 64 71 77 80.5 | |----------------------------------------------------------------------------| 46. | 46 27 33.5 40 46.5 53 60 66.5 72.5 80 | 47. | 47 29.5 37 46 52.5 60 67.5 76 81.5 88 | 48. | 48 28.5 36 42.5 49 55 63.5 72 78.5 85.5 | +----------------------------------------------------------------------------+ . . list in 1/5 +----------------------------------------------------------------------------+ | id week1 week2 week3 week4 week5 week6 week7 week8 week9 | |----------------------------------------------------------------------------| 1. | 1 24 32 39 42.5 48 54.5 61 65 72 | 2. | 2 22.5 30.5 40.5 45 51 58.5 64 72 78 | 3. | 3 22.5 28 36.5 41 47.5 55 61 68 76 | 4. | 4 24 31.5 39.5 44.5 51 56 59.5 64 67 | 5. | 5 24.5 31.5 37 42.5 48 54 58 63 65.5 | +----------------------------------------------------------------------------+ . . describe Contains data from pigs.dta obs: 48 vars: 10 27 Jan 2008 15:17 size: 2,112 (99.8% of memory free) ------------------------------------------------------------------------------- storage display value variable name type format label variable label ------------------------------------------------------------------------------- id float %9.0g week1 float %9.0g week2 float %9.0g week3 float %9.0g week4 float %9.0g week5 float %9.0g week6 float %9.0g week7 float %9.0g week8 float %9.0g week9 float %9.0g ------------------------------------------------------------------------------- Sorted by: Note: dataset has changed since last saved . . save "pigs.dta", replace file pigs.dta saved . *reshape the dataset into long format; . . reshape long week, i(id) j(visit) (note: j = 1 2 3 4 5 6 7 8 9) Data wide -> long ----------------------------------------------------------------------------- Number of obs. 48 -> 432 Number of variables 10 -> 3 j variable (9 values) -> visit xij variables: week1 week2 ... week9 -> week ----------------------------------------------------------------------------- . . sort id visit . . list in 1/5 +-------------------+ | id visit week | |-------------------| 1. | 1 1 24 | 2. | 1 2 32 | 3. | 1 3 39 | 4. | 1 4 42.5 | 5. | 1 5 48 | +-------------------+ . . * Plot in fig3.1 in DHLZ . . ** wrong spaghetti plot ** . . twoway line week visit, s(i) ytitle(weight (kg)) xtitle(time (weeks)) . . ** correct spaghetti plot ** . . twoway line week visit, connect(ascending) s(i) ytitle(weight (kg)) xtitle(time (weeks)) . *To obtain Fig3.2 in DHLZ: . . . . reshape wide (note: j = 1 2 3 4 5 6 7 8 9) Data long -> wide ----------------------------------------------------------------------------- Number of obs. 432 -> 48 Number of variables 3 -> 10 j variable (9 values) visit -> (dropped) xij variables: week -> week1 week2 ... week9 ----------------------------------------------------------------------------- . . *One way of generating the standardized weight . . summarize week1 Variable | Obs Mean Std. Dev. Min Max -------------+-------------------------------------------------------- week1 | 48 25.02083 2.468866 20 31 . . gen sweek1=(week1-25.02)/2.47 . . . . * A simpler way: . . drop sweek1 . . egen sweek1=std(week1) . . egen sweek2=std(week2) . . egen sweek3=std(week3) . . egen sweek4=std(week4) . . egen sweek5=std(week5) . . egen sweek6=std(week6) . . egen sweek7=std(week7) . . egen sweek8=std(week8) . . egen sweek9=std(week9) . . . . reshape long week sweek, i(id) j(visit) (note: j = 1 2 3 4 5 6 7 8 9) Data wide -> long ----------------------------------------------------------------------------- Number of obs. 48 -> 432 Number of variables 19 -> 4 j variable (9 values) -> visit xij variables: week1 week2 ... week9 -> week sweek1 sweek2 ... sweek9 -> sweek ----------------------------------------------------------------------------- . . sort id visit . . twoway line sweek visit, connect(ascending) s(i) ytitle(Residual) xtitle(Time (weeks)) . . . . *Linear regression; . . regress week visit Source | SS df MS Number of obs = 432 -------------+------------------------------ F( 1, 430) = 5757.41 Model | 111060.882 1 111060.882 Prob > F = 0.0000 Residual | 8294.72677 430 19.2900622 R-squared = 0.9305 -------------+------------------------------ Adj R-squared = 0.9303 Total | 119355.609 431 276.927167 Root MSE = 4.392 ------------------------------------------------------------------------------ week | Coef. Std. Err. t P>|t| [95% Conf. Interval] -------------+---------------------------------------------------------------- visit | 6.209896 .0818409 75.88 0.000 6.049038 6.370754 _cons | 19.35561 .4605447 42.03 0.000 18.45041 20.26081 ------------------------------------------------------------------------------ . . . . *Close the log file . . log close log: C:\Documents and Settings\Sandrah Eckel\Desktop\LDA lab1\lab1.log log type: text closed on: 27 Jan 2008, 15:18:01 --------------------------------------------------------------------------------------------------------------------------------------