@Tom  Thank you! I tried as you suggested. In the "want" result data, the order of the itemID is not as I desired. The itemID should be in ascending order in the resulted "want" data. How should I modify your code? ... View more

Here is a very small example data set and some proc freq code: data example; input a $ b c; datalines; a 1 2 a 1 3 a 1 5 a 2 3 a 2 5 a 2 2 b 1 1 b 1 1 b 2 2 b 2 2 b 3 1 c 1 4 c 2 1 ; proc freq data=example; tables b c; run; Running that proc freq generates output like Cumulative Cumulative b Frequency Percent Frequency Percent 1 6 46.15 6 46.15 2 6 46.15 12 92.31 3 1 7.69 13 100.00 Cumulative Cumulative c Frequency Percent Frequency Percent 1 4 30.77 4 30.77 2 4 30.77 8 61.54 3 2 15.38 10 76.92 4 1 7.69 11 84.62 5 2 15.38 13 100.00 So, from that output, which values of the variable A should be attached to which values of B and C in the above output? The more repeated values you have the harder it is going to be to decide which item_id goes with which frequency count result. Anything that adds variables in proc freq is going to change your counts.   So, Show some example data, which you haven't because I have to make decisions on how to turn your CSV into a SAS data set and my choices may not be compatible with your data set. Then show the desired output.   And it may be that if you did any processing to create that data was just making your data more complex.   ... View more

@PGStats  Thanks much for your reply! I need to write SAS code based on the following code. From the code below, does that mean Newton Raphson iteration is needed? If yes, could you please direct me how to do that? FIY, "try" in the code below is the "try.csv" as in the attachment. Thanks a bunch!   LOOP K = 1 TO 150. COMPUTE theta_lo={-20}. COMPUTE theta_hi={20}. COMPUTE delta={.000001}. COMPUTE cut={K}. COMPUTE theta={0}. COMPUTE low={theta_lo}. COMPUTE hi={theta_hi}. COMPUTE IPROB=MAKE(NITEM,1,0). COMPUTE IINFO=MAKE(NITEM,1,0). LOOP. LOOP J=1 TO NITEM. COMPUTE IPROB(J)=(exp(theta-try(J,2))/(1+exp(theta-try(J,2))))). COMPUTE IINFO(J)=IPROB(J)*(1-IPROB(J)). END LOOP. COMPUTE TCC=CSUM(IPROB). DO IF (tcc-cut>delta). COMPUTE hi = theta. COMPUTE theta=theta-ABS((theta-low))/2. END IF. DO IF (tcc-cut< (-1*delta)). COMPUTE low=theta. COMPUTE theta=theta+ABS((hi-theta))/2. END IF. END LOOP IF (abs(tcc-cut)<=delta). ... View more