BookmarkSubscribeRSS Feed
lboyd
Calcite | Level 5

I have data from a pre-assessment and a post-assessment.  Each question/statement was coded as dichotomous (yes/no).  I took the sum of the questions for both pre (shown below) and post using an array:

array xst_itp [12] xst_1 xst_2 xst_3 xst_4 xst_5 xst_6 xst_7 xst_8 xst_9 xst_10 xst_11 xst_12;
        pre_tot = sum(of xst_itp[*]);
        pre_miss_n = cmiss(of xst_itp[*]);
        if st_miss_n  = 12 then st_complete =  0;
        if st_miss_n  < 12 then st_complete =  1;

 

I then ran a simple paired ttest:

proc ttest data = all_data;
paired pre_tot*post_tot;

run;

 

My question is, is it okay to treat this data as continuous data?  Do I need to treat it as count/discrete instead? If so, what analysis would you suggest in SAS?

My other question is, do I need to check the normality of both pre_tot and post_tot? And if one is not normal, do I need to use a Wilcoxon signed-rank test instead?

1 REPLY 1
Reeza
Super User

@lboyd wrote:

 

My question is, is it okay to treat this data as continuous data?  Do I need to treat it as count/discrete instead? If so, what analysis would you suggest in SAS?

 


That's more of a subject specific question in my opinion. 

It depends on how you coded things and such. It's more counts really than a continuous distribution. 

 


My other question is, do I need to check the normality of both pre_tot and post_tot? And if one is not normal, do I need to use a Wilcoxon signed-rank test instead?


You should check the normality, but I think the assumption still holds if the distributions are the same. 

SAS Innovate 2025: Call for Content

Are you ready for the spotlight? We're accepting content ideas for SAS Innovate 2025 to be held May 6-9 in Orlando, FL. The call is open until September 25. Read more here about why you should contribute and what is in it for you!

Submit your idea!

What is Bayesian Analysis?

Learn the difference between classical and Bayesian statistical approaches and see a few PROC examples to perform Bayesian analysis in this video.

Find more tutorials on the SAS Users YouTube channel.

Click image to register for webinarClick image to register for webinar

Classroom Training Available!

Select SAS Training centers are offering in-person courses. View upcoming courses for:

View all other training opportunities.

Discussion stats
  • 1 reply
  • 785 views
  • 0 likes
  • 2 in conversation