topic Re: Calculate change - novice need help in SAS Programming

Calculate change - novice need help

Mmignon — Tue, 22 May 2018 18:09:21 GMT

Hello fellow SAS-users

I'm working on a research project, where I have to compare if there is any significant change in variables on 5 different times (TIME 1-5) in 2 randomisation groups (Randomisation_code 0 and 1) (see dataset). I need to compare them as change from time 1 to 2, 2 to 3 etc. but also over the time at last.
Variables are defined as continuous and categorical (i.e. A1=continuous, A1_pathological = categorical).
I have, so far, just made counting of variables with 'proc freq' and stratified by randomisation_code, and in addition made testing by chisq.

I am very (as very much!) new to SAS and I do not know how to move forward and manage this problem.
I will appreciate any help and step-by-step explanation.

Thanks in advance!
Sincerely
Mignon

Re: Calculate change - novice need help

Reeza — Tue, 22 May 2018 19:42:00 GMT

Its not clear what you need help with here. It would help to not provide excel file, but provide sample data directly in the post and show an example of what you want in the output. Many places do not allow users to download XLSX files to the system.

Re: Calculate change - novice need help

Mmignon — Tue, 22 May 2018 19:57:37 GMT

Hi Reeza

Thank you for fast reply!

I do not know how to explain my problem, but I'll try with an example:

1) I need to see if there is change in variable 'A1_patological' from 'time 1' to 'time 2' to 'time 3' to 'time 4' to 'time 5' in total and afterwards stratified by randomisation code (0 or 1).

My participants does not necessary have measured A1 at all 5 time points.

2) as above, just to see if variable 'A1' (continuous value) is changing (raising or falling) at this 5 time points in total and afterwards stratified by randomisation code (0 or 1).

I suppose that I can present data as a diagram.

I hope the data set is visible now with a copy and paste from Excel-file. Wasn't it that I should do?

Sincerely

Mignon

ParticipantID_and_time	Randomisation_code	P_pr_min	A1	A1_patological	A2	A2_patological	A3	A3_patological	A4	A4_patological	A5	A5_patological	A_max_dur	A_max_dur_patological	TIME
ID1time1	0	73	-0,25	1	-0,25	1	-3,25	1	0	0	0	0	80	1	1
ID1time2	0	77	-0,25	1	-0,5	1	-4	1	0	0	0	0	100	1	2
ID1time3	0	88	-0,25	1	-0,25	1	0	0	0	0	-0,25	1	40	1	3
ID1time4	0	144	-0,5	1	-0,25	1	-2,5	1	0	0	-0,25	1	60	1	4
ID1time5	0	96	-0,5	1	0	0	-2	1	0	0	-0,25	1	60	1	5
ID2time1	0	93	0	0	-0,512820513	0	-0,769230769	1	-13,84615385	1	0	0	61,53846154	1	1
ID2time2	0	81	0	0	0	0	0	0	-7,435897436	1	-0,769230769	1	102,5641026	1	2
ID3time1	0	79	-0,5	1	-0,25	1	0	0	0	0	-0,25	1	80	1	1
ID3time2	0	54	0	0	-0,25	1	-1,25	1	-3	1	0	0	80	1	2
ID3time5	0	67	0	0	0	0	-1	1	-2,5	1	0	0	20	0	5
ID4time1	1	114	.	.	.	.	.	.	.	.	.	.	30	1	1
ID4time4	1	91	0	0	-0,75	1	-1,25	1	-7	1	0	0	40	1	4
ID4time5	1	82	0	0	-1,25	1	-4	1	0	0	0	0	40	1	5
ID5time1	0	85	-0,5	1	-0,5	1	-0,25	1	0	0	-0,5	1	80	1	1
ID5time2	0	59	0	0	-1	1	-1	1	0	0	0	0	80	1	2
ID5time3	0	89	0	0	-1	1	-0,5	1	0	0	0	0	60	1	3
ID5time4	0	104	0	0	-1,25	1	0	0	-7,5	1	0	0	60	1	4

Re: Calculate change - novice need help

Reeza — Tue, 22 May 2018 20:09:51 GMT

1. Switch your data to a long format, it's easier to program your logic that way -> PROC TRANSPOSE or a DATA STEP.

https://stats.idre.ucla.edu/sas/modules/reshaping-data-wide-to-long-using-a-data-step/

https://stats.idre.ucla.edu/sas/modules/how-to-reshape-data-wide-to-long-using-proc-transpose/

2. Use LAG to find the difference between the time points

http://support.sas.com/resources/papers/proceedings09/055-2009.pdf

3. Once you have that, you have the data to do your tests, which I think I answered in another post - you can use PROC MEANS to calculate the total change, or you can use PROC NPAR1WAY to test the values.

Re: Calculate change - novice need help

Mmignon — Tue, 22 May 2018 20:17:10 GMT

Thank you Reeza

I'll try work on it!

Sincerely
Mignon