I am having a problem correcting dates in my sas file. I already have all set sas files with dates DDMMYYYY (like 02/10/2011). Ok, but then I found that some of my dates (form some individuals) are incorrect and I want to correct it in a date step.  Lets supose I have the individual ID = 201 with a interview date (interdate) = 02/10/2011 but I want to correct this date to 02/12/2011.  I tried mane ways and I wasnt able to figure that out. I tried the date numbers between quota, with slash, with hifen....and so on. I also tried to format again the variable.  Does anybody can help me...? I will have to correct several dates. I don´t want to have to export to excell every time then correct there and then import again into SAS...   the original enterdata is correct in the format like 02/10/2011, and it is working ok, I already caculated age of individuals from their birth date and so on.    data old; se new; if ind = 201 then enterdata  = 02122011;  run;       ... View more

I am doing analysis of a trial testing satisfaction in VA scale from 0 to 100 in a cross over trial. Patients were assigned to two treatment and followed for 12 months. After the 12 month the treatment was changed and followed for another 12 months.  Measures of satisfaction were perfomed at the first week, then at 3 months , 6 months and 12 months (4 times).    Distribution was not normal very skewed to the right.  I tried some different distributions such as exp and poisson, but residuals are not randomly distributed around zero, specially a the end it positive residuals drasticlly decreases to zero. Independent of the distribution I used , even normal residuals are very similar.  Q2 is satisfaction.  This is what I am using.  proc glimmix plots = all ; class paciente treat (ref = first) time (ref= first); model q2 = treat | time /solution link = log s dist = poisson ; random int /subject = paciente; covtest 'var(paciente) = 0' 0 .; run;   Would overdispersion be a problem and a beta binomial be recommended?    Thanks so much.    ... View more

  A friend of mine asked me if I knew why a kruskall-wallis test of scores had significant p value of 0.003 and the Dunns test showed no statistical significant results.  One person told us to look at quartiles to see the difference. Is it ok to do that? An why Dunns test would not show where were the differences?  Thanks so much. Maria   ... View more

I am doing analysis of a scores ( 0 to 5) taken repeatedly over time (21 consecutive sectionsequally spaced)  in two treatment groups. Since it is not normally distributed which would be the best statistical procedure? I am not statistician, I am epidemiologist. I usually work with repeated measures with normal distribution using mixed models and so.. but I am having trouble to get the best analysis for these scores. I was reading about harsh models but I am not sure if it would be appropriate. Would rasch model appropriated? It would sum up items for individuals but I am not sure if it would work. It is the same measure over time.    ... View more