Hi all,  I'm doing a school project on complications occurring within 30-days post-op, it was defined as a binary variable.  The sample is small (n = 139) and we have decided on 5 variables: Age (continuous) Comorbidities (binary) Diagnosis type (3 class category) Treatment type (3 class category) Sex (binary) Now, I've done collinearity, univariate logistic analyses, and then eventually onto the multivariate logistic. It was stable, everything looked great.  My supervisor suggested looking at 2 additional numeric variables which were also part of our dataset; in clinical terms, it would pose a great question and it has to do with treatment. So I did some exploratory work. I looked into the variables, performed the same steps of looking into scatter plots, univariate, etc etc. I tried the full model with 7 variables and again, stable. The output wasn't far from the initial with 5.    However, should I change the code and add units age = 5; SAS would not output it. I'm sure it has to do with sample size, but could someone help me understand the background of this.  ... View more

I'm using a data set called groin; it collects data on groin dissection surgery.  Y is a binary dummy variable for any complications.  X's include patient, disease, and treatment characteristics. This is but a sample of my data and it includes wound infection (binary), wound necrosis (binary), mitosis (binary), patient cancer status (binary), and operative time in min (continuous).    I've done assessments in frequencies and univariate logistic models; everything went smoothly.  data groin (keep = patient_id comp wnd_inf wnd_nec mitosis stats op_time); set raw_data; /*Complications*/ if comp_w = 'yes' then comp = '1'; if comp_w = 'no' then comp = '0'; /*Wound infection*/ if wnd_w = 'yes' then wnd_inf= '1'; if wnd_w = 'no' then wnd_inf = '0'; /*Wound necrosis*/ if nec_w = 'yes' then wnd_nec = '1'; if nec_w = 'no' then wnd_nec = '0'; /*Mitosis*/ if mit_w = ' 'yes' then mitosis = '1'; if mit_w = 'no' then mitosis = '0'; /*Current cancer status*/ if pt_stat = 'cancer free' then stats = '0'; if pt_stat = 'recurred' then stats = '1'; run; /*Example of univariate log reg*/ proc logisitc data = groin descending; class mitosis (ref = '0') /param = ref; model comp = mitosis/ clodds = wald orpvalue; run; However, when doing the full model following this code, the error of INVALID REFERENCE VALUE shows up for mitosis proc logisitc data = groin descending; class mitosis (ref = '0') wnd_inf (ref = '0') wnd_nec (ref = '0') stats (ref = '0') op_time /param = ref; model comp = wnd_inf wnd_nec mitosis stats op_time / clodds = wald orpvalue; run; Why would it work in the small model but not the full?     Here is the log that accompanies my real code /*Small model*/ 9543 proc logistic data = ga_2 descending; /*Desceding puts complication = 1 as the 9543! reference group*/ 9544 /*Therefore it acesses the 9544! probability of having complication*/ 9545 class sex_num (ref = '0') 9546 thickness_num (ref = '0') 9547 hist_num (ref = '0') 9548 mitosis_bin (ref = '0') 9549 ulcer_num (ref = '0') 9550 lvi_num (ref = '0') 9551 regression_num (ref = '0') 9552 smoker_num (ref = '0') 9553 diabetes_num (ref = '0') 9554 card_num (ref = '0') 9555 hypo_th_num (ref = '0') 9556 staff (ref = '1') 9557 present_num (ref = '0') 9558 indication_num (ref = '0') 9559 dissec_num (ref = '0') 9560 op_time 9561 blood_loss 9562 dur_immobile 9563 dur_postop_ab 9564 hosp_stay 9565 tot_ln 9566 tot_pos_ln 9567 neo_num (ref = '0') 9568 sys_num (ref = '0') 9569 adj_rt_num (ref = '0') 9570 recur_site_num (ref = '1') 9571 /param = ref; 9572 9573 model COMP_NUM = 9574 sex_num 9575 thickness_num hist_num 9576 mitosis_bin 9577 ulcer_num lvi_num regression_num 9578 smoker_num diabetes_num card_num 9579 hypo_th_num 9580 staff present_num indication_num 9581 dissec_num op_time blood_loss no_drains_left 9581! dur_immobile dur_postop_ab hosp_stay 9582 tot_ln tot_pos_ln 9583 neo_num sys_num adj_rt_num 9584 recur_site_num 9585 / clodds = wald orpvalue; 9586 title 'Multivariate Analyses, all variables'; run; ERROR: Invalid reference value for mitosis_bin. NOTE: The SAS System stopped processing this step because of errors. NOTE: There were 141 observations read from the data set WORK.GA_2. NOTE: PROCEDURE LOGISTIC used (Total process time): real time 0.00 seconds cpu time 0.00 seconds ... View more

Consider the data set below where the variable 'tot' states the total number of correct answers and where 'mark' states the percentage score of that test.  data have; input id $ tot1 tot2 tot3 tot4 tot5 tot6 mark11 mark12 mark21 mark22 mark31 mark32; x 4 2 0 5 6 0 0.4 0.2 0.0 0.5 0.6 0.0 y 7 3 2 2 7 8 0.7 0.3 0.2 0.2 0.7 0.8 x 10 8 4 0 1 3 1.0 0.8 0.4 0.0 0.1 0.3 ; run; I'm looking to create a new count variable to identify the number of tests where the scores are of passing grade (above 50%) and only consider any column starting with "MARK" and ends with a '2', but having trouble on how to write the conditional code.  The following table is what I aim to achieve, but I'm quite clueless on how to get there. I only want to consider MARK12, MARK22, and MARK32. ID TOT1 TOT2 TOT3 TOT4 TOT5 TOT6 MARK1 MARK12 MARK21 Mark22 MARK31 MARK32 NO_TEST X 4 2 0 5 6 0 0.4 0.2 0.0 0.5 0.6 0.0 1 Y 7 3 2 2 7 8 0.7 0.3 0.2 0.2 0.7 0.8 1 Z 10 8 4 0 1 3 1.0 0.8 0.4 0.0 0.1 0.3 1 Thank you in advance!   ... View more

Hi there,    The following is my current dataset.  Fst_pl represents the first and most expensive plastic surgery procedural code per patient.    I've used the following code to sort it:  proc sort data = comp_3; out = comp_4; by pid pl_date descending bill_amount; run; My question is as follows: These patients have "COMPLEX" as their most expensive billed code for their first plastic surgery. This is a supplementary code that simply added on top to the actual procedural code to correctly bill the surgeon doing the work. So, what I'd like to identify is the next most expensive code matched on the same day.    How do I retain all dates matching onto the FIRST recorded pl_date per patient? Or at least, how do I retain 2 lines of code for each patient stating the most and second most expensive procedures on the earliest recorded surgery? I've had ideas as to using a combination of IF ELSE and FIRST statements, but have not been successful.  ... View more