I tried two solutions and I'll give you the outcome to see what you think. I appreciate you helping by the way. First, I ditched the quotations around MLV1. Ran the code and got this result:   title 'EWMA chart for farrowing rate per week, Farm_ID=CRC'; graphics on; symbol v=dot; proc MACONTROL data=work.a limits=c; where (Farm_Name="RVL") & (weeks ge 1) & (interventions=MLV1) /* & (status ne 'extra')*/  ; ERROR: Variable MLV1 is not on file WORK.A.  ewmachart Aborts * weeks/  /* ewmachart Wean_ * week/*/  WEIGHT = 0.4  meansymbol = square  /* lcllabel = 'LCL for EWMA' ucllabel = 'UCL for EWMA'*/  vreflabpos = 3 Asymptotic  outhistory = outEWMA;  /*label status = "Status infeccao"*/  /* week = "weeks post infection";*/  run; NOTE: The SAS System stopped processing this step because of errors. WARNING: The data set WORK.OUTEWMA may be incomplete. When this step was stopped there were 0 observations and 0 variables. WARNING: Data set WORK.OUTEWMA was not replaced because this step was stopped.   Then I tried changing it to interventions=1, and got this result:   title 'EWMA chart for farrowing rate per week, Farm_ID=CRC'; ods graphics on; symbol v=dot; proc MACONTROL data=work.a limits=c; where (Farm_Name="RVL") & (weeks ge 1) & (interventions=1)  /* & (status ne 'extra')*/  ;  ewmachart Aborts * weeks/  /* ewmachart Wean_ * week/*/  WEIGHT = 0.4  meansymbol = square  /* lcllabel = 'LCL for EWMA' ucllabel = 'UCL for EWMA'*/  vreflabpos = 3 Asymptotic  outhistory = outEWMA;  /*label status = "Status infeccao"*/  /* week = "weeks post infection";*/  run; NOTE: No observations were selected from data set WORK.A. NOTE: There were 0 observations read from the data set WORK.A. WHERE (Farm_Name='RVL') and (weeks>=1) and (interventions=1); NOTE: The data set WORK.OUTEWMA has 0 observations and 0 variables. WARNING: Data set WORK.OUTEWMA was not replaced because new file is incomplete.   Hopefully this helps, not sure what it all really means. ... View more

Thanks for the speedy reply! So according to the list of variables and attributes produced by the "proc contents data", Farm_name is a character, weeks is a numeric value, and interventions is a numeric value, not a character like you said it should be. So my next question is, how do I change this? In original excel doc? Thanks. ... View more