Hi,

I am using Stata 17 and would need help in extracting start dates. My intention is to extract start dates of each recession and expansion. Below is an example of my dataset:

Code:
* Example generated by -dataex-. For more info, type help dataex
clear
input str10 observation_date float(unrate NBER_peaks NBER_troughs) byte usrec double(date datem)
"1948-01-01" 3.4 0 0 0 -4383 -144
"1948-02-01" 3.8 0 0 0 -4352 -143
"1948-03-01"   4 0 0 0 -4323 -142
"1948-04-01" 3.9 0 0 0 -4292 -141
"1948-05-01" 3.5 0 0 0 -4262 -140
"1948-06-01" 3.6 0 0 0 -4231 -139
"1948-07-01" 3.6 0 0 0 -4201 -138
"1948-08-01" 3.9 0 0 0 -4170 -137
"1948-09-01" 3.8 0 0 0 -4139 -136
"1948-10-01" 3.7 0 0 0 -4109 -135
"1948-11-01" 3.8 1 0 0 -4078 -134
"1948-12-01"   4 0 0 1 -4048 -133
"1949-01-01" 4.3 0 0 1 -4017 -132
"1949-02-01" 4.7 0 0 1 -3986 -131
"1949-03-01"   5 0 0 1 -3958 -130
"1949-04-01" 5.3 0 0 1 -3927 -129
"1949-05-01" 6.1 0 0 1 -3897 -128
"1949-06-01" 6.2 0 0 1 -3866 -127
"1949-07-01" 6.7 0 0 1 -3836 -126
"1949-08-01" 6.8 0 0 1 -3805 -125
"1949-09-01" 6.6 0 0 1 -3774 -124
"1949-10-01" 7.9 0 1 1 -3744 -123
"1949-11-01" 6.4 0 0 0 -3713 -122
"1949-12-01" 6.6 0 0 0 -3683 -121
"1950-01-01" 6.5 0 0 0 -3652 -120
"1950-02-01" 6.4 0 0 0 -3621 -119
"1950-03-01" 6.3 0 0 0 -3593 -118
"1950-04-01" 5.8 0 0 0 -3562 -117
"1950-05-01" 5.5 0 0 0 -3532 -116
"1950-06-01" 5.4 0 0 0 -3501 -115
"1950-07-01"   5 0 0 0 -3471 -114
"1950-08-01" 4.5 0 0 0 -3440 -113
"1950-09-01" 4.4 0 0 0 -3409 -112
"1950-10-01" 4.2 0 0 0 -3379 -111
"1950-11-01" 4.2 0 0 0 -3348 -110
"1950-12-01" 4.3 0 0 0 -3318 -109
"1951-01-01" 3.7 0 0 0 -3287 -108
"1951-02-01" 3.4 0 0 0 -3256 -107
"1951-03-01" 3.4 0 0 0 -3228 -106
"1951-04-01" 3.1 0 0 0 -3197 -105
"1951-05-01"   3 0 0 0 -3167 -104
"1951-06-01" 3.2 0 0 0 -3136 -103
"1951-07-01" 3.1 0 0 0 -3106 -102
"1951-08-01" 3.1 0 0 0 -3075 -101
"1951-09-01" 3.3 0 0 0 -3044 -100
"1951-10-01" 3.5 0 0 0 -3014  -99
"1951-11-01" 3.5 0 0 0 -2983  -98
"1951-12-01" 3.1 0 0 0 -2953  -97
"1952-01-01" 3.2 0 0 0 -2922  -96
"1952-02-01" 3.1 0 0 0 -2891  -95
"1952-03-01" 2.9 0 0 0 -2862  -94
"1952-04-01" 2.9 0 0 0 -2831  -93
"1952-05-01"   3 0 0 0 -2801  -92
"1952-06-01"   3 0 0 0 -2770  -91
"1952-07-01" 3.2 0 0 0 -2740  -90
"1952-08-01" 3.4 0 0 0 -2709  -89
"1952-09-01" 3.1 0 0 0 -2678  -88
"1952-10-01"   3 0 0 0 -2648  -87
"1952-11-01" 2.8 0 0 0 -2617  -86
"1952-12-01" 2.7 0 0 0 -2587  -85
"1953-01-01" 2.9 0 0 0 -2556  -84
"1953-02-01" 2.6 0 0 0 -2525  -83
"1953-03-01" 2.6 0 0 0 -2497  -82
"1953-04-01" 2.7 0 0 0 -2466  -81
"1953-05-01" 2.5 0 0 0 -2436  -80
"1953-06-01" 2.5 0 0 0 -2405  -79
"1953-07-01" 2.6 1 0 0 -2375  -78
"1953-08-01" 2.7 0 0 1 -2344  -77
"1953-09-01" 2.9 0 0 1 -2313  -76
"1953-10-01" 3.1 0 0 1 -2283  -75
"1953-11-01" 3.5 0 0 1 -2252  -74
"1953-12-01" 4.5 0 0 1 -2222  -73
"1954-01-01" 4.9 0 0 1 -2191  -72
"1954-02-01" 5.2 0 0 1 -2160  -71
"1954-03-01" 5.7 0 0 1 -2132  -70
"1954-04-01" 5.9 0 0 1 -2101  -69
"1954-05-01" 5.9 0 1 1 -2071  -68
"1954-06-01" 5.6 0 0 0 -2040  -67
"1954-07-01" 5.8 0 0 0 -2010  -66
"1954-08-01"   6 0 0 0 -1979  -65
"1954-09-01" 6.1 0 0 0 -1948  -64
"1954-10-01" 5.7 0 0 0 -1918  -63
"1954-11-01" 5.3 0 0 0 -1887  -62
"1954-12-01"   5 0 0 0 -1857  -61
"1955-01-01" 4.9 0 0 0 -1826  -60
"1955-02-01" 4.7 0 0 0 -1795  -59
"1955-03-01" 4.6 0 0 0 -1767  -58
"1955-04-01" 4.7 0 0 0 -1736  -57
"1955-05-01" 4.3 0 0 0 -1706  -56
"1955-06-01" 4.2 0 0 0 -1675  -55
"1955-07-01"   4 0 0 0 -1645  -54
"1955-08-01" 4.2 0 0 0 -1614  -53
"1955-09-01" 4.1 0 0 0 -1583  -52
"1955-10-01" 4.3 0 0 0 -1553  -51
"1955-11-01" 4.2 0 0 0 -1522  -50
"1955-12-01" 4.2 0 0 0 -1492  -49
"1956-01-01"   4 0 0 0 -1461  -48
"1956-02-01" 3.9 0 0 0 -1430  -47
"1956-03-01" 4.2 0 0 0 -1401  -46
"1956-04-01"   4 0 0 0 -1370  -45
end
format %td date
format %tm datem
The variable "usrec" is equal to 1 if there is a recession and 0 if there is expansion. What I want to do is the extract the start dates of each recession and expansion. So ideally I want one column for expansion start dates and another column for recession start dates. For example, the first recession start date is at Dec 1948 and second recession start date is at Aug 1953. So the recession column should have these dates as the first 2 observations.

I am not sure which commands to use to extract start dates. Any help in this area would be appreciated.

Thanks!