Working with dates

[Fredrick orwa]

Hae, am planning to start a data collection on 29/03/2020 for my project. Being the data manager of this project I will be required to generate weekly progress reports. I need help in generating a code that start counting as from 29/03/2020 to 04/04/2020 as week 1 and so on.Instead of counting weeks from 1st Jan 2020.Kindly help.

[Nick Cox]

Stata weeks are no use to you here. You have your own origin and each week is a block of 7 days starting then.

clear
set obs 366
gen day = mdy(3, 28, 2020) + _n 
egen week = seq(), block(7)
format day %td
l in 1/49, sep(7)

    +------------------+
     |       day   week |
     |------------------|
  1. | 29mar2020      1 |
  2. | 30mar2020      1 |
  3. | 31mar2020      1 |
  4. | 01apr2020      1 |
  5. | 02apr2020      1 |
  6. | 03apr2020      1 |
  7. | 04apr2020      1 |
     |------------------|
  8. | 05apr2020      2 |
  9. | 06apr2020      2 |
 10. | 07apr2020      2 |
 11. | 08apr2020      2 |
 12. | 09apr2020      2 |
 13. | 10apr2020      2 |
 14. | 11apr2020      2 |
     |------------------|
 15. | 12apr2020      3 |
 16. | 13apr2020      3 |
 17. | 14apr2020      3 |
 18. | 15apr2020      3 |
 19. | 16apr2020      3 |
 20. | 17apr2020      3 |
 21. | 18apr2020      3 |
     |------------------|
 22. | 19apr2020      4 |
 23. | 20apr2020      4 |
 24. | 21apr2020      4 |
 25. | 22apr2020      4 |
 26. | 23apr2020      4 |
 27. | 24apr2020      4 |
 28. | 25apr2020      4 |
     |------------------|
 29. | 26apr2020      5 |
 30. | 27apr2020      5 |
 31. | 28apr2020      5 |
 32. | 29apr2020      5 |
 33. | 30apr2020      5 |
 34. | 01may2020      5 |
 35. | 02may2020      5 |
     |------------------|
 36. | 03may2020      6 |
 37. | 04may2020      6 |
 38. | 05may2020      6 |
 39. | 06may2020      6 |
 40. | 07may2020      6 |
 41. | 08may2020      6 |
 42. | 09may2020      6 |
     |------------------|
 43. | 10may2020      7 |
 44. | 11may2020      7 |
 45. | 12may2020      7 |
 46. | 13may2020      7 |
 47. | 14may2020      7 |
 48. | 15may2020      7 |
 49. | 16may2020      7 |
     +------------------+

For an expansion of my first sentence, see

. search week, sj

Search of official help files, FAQs, Examples, SJs, and STBs

SJ-12-4 dm0065_1  . . . . . Stata tip 111: More on working with weeks, erratum
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q4/12   SJ 12(4):765                                     (no commands)
        lists previously omitted key reference

SJ-12-3 dm0065  . . . . . . . . . .  Stata tip 111: More on working with weeks
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q3/12   SJ 12(3):565--569                                (no commands)
        discusses how to convert data presented in yearly and weekly
        form to daily dates and how to aggregate such data to months
        or longer intervals

SJ-10-4 dm0052  . . . . . . . . . . . . . . . . Stata tip 68: Week assumptions
        . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  N. J. Cox
        Q4/10   SJ 10(4):682--685                                (no commands)
        tip on Stata's solution for weeks and on how to set up
        your own alternatives given different definitions of the
        week

[Andrew Musau]

The date 29/03/2020 in SIF is a number

. di date("29/03/2020", "DMY")
22003

Because you count duration in days as End- Start+ 1, for any given day, after converting to SIF, you can determine the week number as the ceiling of (date-22003+1)/7. So for example

. di date("04/04/2020", "DMY")
22009


. di ceil((22009-22003+1)/7)
1

and the day after

. di date("05/04/2020", "DMY")
22010

. di ceil((22010-22003+1)/7)
2