I want to calculate mean time between two survey responses. I am working with a survey data with five follow-ups. Questionnaires were sent every three years. So, gap between each follow up is of three years. In my data, I have an indicator variable “survey no.” with values 1, 2, 3, 4, 5. Time between survey no.=1 and survey no.=2 is 3 years, between survey no. =1 and survey no. =3 is 6 years. The longest possible gap between survey no. =1 and survey no. =5 is 12 years. In my study I included participants who responded minimum of two survey but I have some participants who responded to all surveys, some to three surveys, and some to two surveys. This gives multiple combinations of number of years per id between two surveys. I have a made up sample below. data have;
input ID survey no. exposure;
1 2 0
1 3 1
2 1 1
2 1 1
2 3 0
2 4 0
2 5 1
3 1 0
3 2 1
3 3 1
3 4 0
3 5 1
;
run; In an attached image, I tried to explain possible combinations between survey response per id. I tried to make a syntax but it is complicated that I thought. I am new to SAS and reluctant to suggest any code.
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