Hi all
I'm looking to work out the difference in effect (time to surgery) between two patient populations (exposed and unexposed groups) and compare between two countries (i.e. difference in differences).
I have tried using the didregress command below although am getting the error "invalid group specification. None of the groups defined by country is a control.". Not really sure what this means and how to fix it. I have checked that i have fairly good numbers in all four variables below when i cross-tab them.
didregress (timetosurgeryinhours) (patient_anticoagulant_med), group(country) time(month10)
any help would be much appreciated
here is some of my data
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------------------ copy up to and including the previous line ------------------
. tab country month10
month10
country 5 6 7 Total
0 2,756 2,696 2,587 8,039
1 402 416 365 1,183
2 118 111 120 349
3 105 69 66 240
Total 3,381 3,292 3,138 9,811
. tab patient_anticoagulant_med country
Does
patient
take an
anticoagul
ant
medication country
? 0 1 2 3 Total
0 1,503 173 70 52 1,798
Yes 6,538 1,010 279 188 8,015
Total 8,041 1,183 349 240 9,813
I'm looking to work out the difference in effect (time to surgery) between two patient populations (exposed and unexposed groups) and compare between two countries (i.e. difference in differences).
I have tried using the didregress command below although am getting the error "invalid group specification. None of the groups defined by country is a control.". Not really sure what this means and how to fix it. I have checked that i have fairly good numbers in all four variables below when i cross-tab them.
didregress (timetosurgeryinhours) (patient_anticoagulant_med), group(country) time(month10)
any help would be much appreciated
here is some of my data
----------------------- copy starting from the next line -----------------------
Code:
* Example generated by -dataex-. For more info, type help dataex clear input float timetosurgeryinhours byte patient_anticoagulant_med float(country month10) 43.90548 0 0 6 56.73095 0 1 6 14.90566 0 0 7 50.74575 0 0 6 33.193012 0 0 7 18.767643 0 0 7 34.22039 0 0 5 50.06162 0 0 7 18.023438 0 0 6 48.51983 0 0 6 28.820833 0 1 5 22.56784 0 0 6 17.54719 0 0 5 39.43437 0 0 5 6.062158 0 0 6 21.13416 0 0 5 42.54428 0 0 5 18.128193 0 0 7 146.48012 0 0 7 38.038704 0 0 7 46.28093 0 2 5 71.67136 0 0 5 41.37807 0 1 7 32.78094 0 0 6 45.8409 0 0 6 64.999825 0 2 6 52.75509 0 0 6 50.60921 0 0 5 24.00983 0 0 7 41.07802 0 0 6 168.0117 0 0 6 73.433105 0 0 5 134.03046 0 3 5 143.10442 0 0 7 36.26608 0 0 5 43.87835 0 0 5 31.392994 0 0 6 29.4903 0 0 7 17.899597 0 0 5 51.33377 0 0 5 27.9648 0 0 7 35.343395 0 0 7 71.253265 0 0 5 16.164976 0 0 7 22.49412 0 0 6 53.4966 0 0 6 19.040194 0 0 6 52.83084 0 0 6 35.370434 0 0 7 end label values patient_anticoagulant_med patient_anticoagulant_med_ label values country country label def country 0 "england", modify label def country 1 "scotland", modify label def country 2 "wales", modify label def country 3 "NI", modify
. tab country month10
month10
country 5 6 7 Total
0 2,756 2,696 2,587 8,039
1 402 416 365 1,183
2 118 111 120 349
3 105 69 66 240
Total 3,381 3,292 3,138 9,811
. tab patient_anticoagulant_med country
Does
patient
take an
anticoagul
ant
medication country
? 0 1 2 3 Total
0 1,503 173 70 52 1,798
Yes 6,538 1,010 279 188 8,015
Total 8,041 1,183 349 240 9,813
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