How to create a variable with the values of every first observation of each group

[CynthiaWei]

Hi SAS Experts,

I am having a data set like this:

Family	ID	female	Has fiber every day	age	Mother	Kids
4	4	1	1	25	1	0
4	4.1	0	1	29	0	1
4	4.2	1	0	34	0	1
4	4.3	1	1	45	0	1
5	5	1	1	42	1	0
5	5.1	1	1	53	0	1
6	6	1	0	23	1	0
6	6.1	0	0	29	0	1
6	6.2	0	1	36	0	1
7	7	1	1	48	1	0
7	7.1	1	0	23	0	1
8	8	1	0	53	1	0
8	8.1	0	0	54	0	1
8	8.2	1	1	37	0	1
8	8.3	1	1	41	0	1
8	8.4	0	1	26	0	1

So, I want to create some variables representing for only the information of first observation (which is the information for mothers) of every group (the variable here is family).

What I want is as follows: 

New created variables are: whether mother have fiber every day and Mother's age.

Basically, the values for these two variables are the values of mothers from each family and repeat as many times as the number of theirs kids participated in the study. So, in this way I can use paired t-test to compare these dependent variables, such as the mother's age and her kids ages or mother's physical activity hours and kids' physical activity hours (not listed here). For comparison of having fiber every day between mothers and their kids, it should use McNemars' test, right?

Family	ID	female	Whether Mother have fiber every day	Has fiber every day	Mother's age	age	Mother	Kids
4	4	1	1	1	25	25	1	0
4	4.1	0	1	1	25	9	0	1
4	4.2	1	1	0	25	4	0	1
4	4.3	1	1	1	25	6	0	1
5	5	1	1	1	42	42	1	0
5	5.1	1	1	1	42	13	0	1
6	6	1	0	0	23	23	1	0
6	6.1	0	0	0	23	2	0	1
6	6.2	0	0	1	23	4	0	1
7	7	1	1	1	48	48	1	0
7	7.1	1	1	0	48	23	0	1
8	8	1	0	0	53	53	1	0
8	8.1	0	0	0	53	27	0	1
8	8.2	1	0	1	53	24	0	1
8	8.3	1	0	1	53	20	0	1
8	8.4	0	0	1	53	16	0	1

Thank you very much!

Kind regards,

C

[ed_sas_member · Accepted solution]

Hi @CynthiaWei,

Here is some code to creates the two variables:

data have;
	infile datalines dlm=' ' ;
	input Family 1 ID 3-5 female 7 fiber 9 age 11-12 Mother 14 Kids 16;
	datalines;
4 4   1 1 25 1 0
4 4.1 0 1 29 0 1
4 4.2 1 0 34 0 1
4 4.3 1 1 45 0 1
5 5   1 1 42 1 0
5 5.1 1	1 53 0 1
6 6   1 0 23 1 0
6 6.1 0	0 29 0 1
6 6.2 0	1 36 0 1
7 7   1 1 48 1 0
7 7.1 1	0 23 0 1
8 8   1 0 53 1 0
8 8.1 0	0 54 0 1
8 8.2 1	1 37 0 1
8 8.3 1	1 41 0 1
8 8.4 0	1 26 0 1
;
run;

proc sort data=have;
	by family ID; /* assuming the first ID is for the mother */
run;

data want;
	set have;
	by family id;
	
	/* Compute mother's age*/
	retain mother_age;
	if first.family then mother_age = age;

	/* Compute whether mother have fiber every day */
	retain fiber_YN;
	if first.family then fiber_YN = fiber;

run;

if think you can use Mc Nemar's test using a proc freq

[CynthiaWei]

Hi,

Thank you so much for the code. The code worked very well, and my problem has been solved. I really appreciate it a lot!

I apologized that I was not able to respond you any sooner due to the business meetings and traveling.

Kind regards,

Cynthia

[mkeintz]

@CynthiaWei 

I suggest you mark the response by @ed_sas_member as a solution.  This not only recognizes the help provided by respondents but also re-categories your topic as solved - which can help others browsing the forum

regards,

Mark